Alien-FreeImage
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src/Source/FreeImage.h view on Meta::CPAN
DLL_API BOOL DLL_CALLCONV FreeImage_SetComplexChannel(FIBITMAP *dst, FIBITMAP *src, FREE_IMAGE_COLOR_CHANNEL channel);
// copy / paste / composite routines
DLL_API FIBITMAP *DLL_CALLCONV FreeImage_Copy(FIBITMAP *dib, int left, int top, int right, int bottom);
DLL_API BOOL DLL_CALLCONV FreeImage_Paste(FIBITMAP *dst, FIBITMAP *src, int left, int top, int alpha);
DLL_API FIBITMAP *DLL_CALLCONV FreeImage_CreateView(FIBITMAP *dib, unsigned left, unsigned top, unsigned right, unsigned bottom);
DLL_API FIBITMAP *DLL_CALLCONV FreeImage_Composite(FIBITMAP *fg, BOOL useFileBkg FI_DEFAULT(FALSE), RGBQUAD *appBkColor FI_DEFAULT(NULL), FIBITMAP *bg FI_DEFAULT(NULL));
DLL_API BOOL DLL_CALLCONV FreeImage_PreMultiplyWithAlpha(FIBITMAP *dib);
// background filling routines
DLL_API BOOL DLL_CALLCONV FreeImage_FillBackground(FIBITMAP *dib, const void *color, int options FI_DEFAULT(0));
DLL_API FIBITMAP *DLL_CALLCONV FreeImage_EnlargeCanvas(FIBITMAP *src, int left, int top, int right, int bottom, const void *color, int options FI_DEFAULT(0));
DLL_API FIBITMAP *DLL_CALLCONV FreeImage_AllocateEx(int width, int height, int bpp, const RGBQUAD *color, int options FI_DEFAULT(0), const RGBQUAD *palette FI_DEFAULT(NULL), unsigned red_mask FI_DEFAULT(0), unsigned green_mask FI_DEFAULT(0), unsigned...
DLL_API FIBITMAP *DLL_CALLCONV FreeImage_AllocateExT(FREE_IMAGE_TYPE type, int width, int height, int bpp, const void *color, int options FI_DEFAULT(0), const RGBQUAD *palette FI_DEFAULT(NULL), unsigned red_mask FI_DEFAULT(0), unsigned green_mask FI_...
// miscellaneous algorithms
DLL_API FIBITMAP *DLL_CALLCONV FreeImage_MultigridPoissonSolver(FIBITMAP *Laplacian, int ncycle FI_DEFAULT(3));
// restore the borland-specific enum size option
#if defined(__BORLANDC__)
src/Source/FreeImage/BitmapAccess.cpp view on Meta::CPAN
// FIBITMAP definition
// ----------------------------------------------------------
/**
FreeImage header structure
*/
FI_STRUCT (FREEIMAGEHEADER) {
/** data type - bitmap, array of long, double, complex, etc */
FREE_IMAGE_TYPE type;
/** background color used for RGB transparency */
RGBQUAD bkgnd_color;
/**@name transparency management */
//@{
/**
why another table ? for easy transparency table retrieval !
transparency could be stored in the palette, which is better
overall, but it requires quite some changes and it will render
FreeImage_GetTransparencyTable obsolete in its current form;
*/
src/Source/FreeImage/BitmapAccess.cpp view on Meta::CPAN
RGBQUAD *bkgnd_color = &((FREEIMAGEHEADER *)dib->data)->bkgnd_color;
return (bkgnd_color->rgbReserved != 0) ? TRUE : FALSE;
}
return FALSE;
}
BOOL DLL_CALLCONV
FreeImage_GetBackgroundColor(FIBITMAP *dib, RGBQUAD *bkcolor) {
if(dib && bkcolor) {
if(FreeImage_HasBackgroundColor(dib)) {
// get the background color
RGBQUAD *bkgnd_color = &((FREEIMAGEHEADER *)dib->data)->bkgnd_color;
memcpy(bkcolor, bkgnd_color, sizeof(RGBQUAD));
// get the background index
if(FreeImage_GetBPP(dib) == 8) {
RGBQUAD *pal = FreeImage_GetPalette(dib);
for(unsigned i = 0; i < FreeImage_GetColorsUsed(dib); i++) {
if(bkgnd_color->rgbRed == pal[i].rgbRed) {
if(bkgnd_color->rgbGreen == pal[i].rgbGreen) {
if(bkgnd_color->rgbBlue == pal[i].rgbBlue) {
bkcolor->rgbReserved = (BYTE)i;
return TRUE;
}
}
src/Source/FreeImage/BitmapAccess.cpp view on Meta::CPAN
}
return FALSE;
}
BOOL DLL_CALLCONV
FreeImage_SetBackgroundColor(FIBITMAP *dib, RGBQUAD *bkcolor) {
if(dib) {
RGBQUAD *bkgnd_color = &((FREEIMAGEHEADER *)dib->data)->bkgnd_color;
if(bkcolor) {
// set the background color
memcpy(bkgnd_color, bkcolor, sizeof(RGBQUAD));
// enable the file background color
bkgnd_color->rgbReserved = 1;
} else {
// clear and disable the file background color
memset(bkgnd_color, 0, sizeof(RGBQUAD));
}
return TRUE;
}
return FALSE;
}
// ----------------------------------------------------------
src/Source/FreeImage/PluginGIF.cpp view on Meta::CPAN
// ==========================================================
// Constant/Typedef declarations
// ==========================================================
struct GIFinfo {
BOOL read;
//only really used when reading
size_t global_color_table_offset;
int global_color_table_size;
BYTE background_color;
std::vector<size_t> application_extension_offsets;
std::vector<size_t> comment_extension_offsets;
std::vector<size_t> graphic_control_extension_offsets;
std::vector<size_t> image_descriptor_offsets;
GIFinfo() : read(0), global_color_table_offset(0), global_color_table_size(0), background_color(0)
{
}
};
struct PageInfo {
PageInfo(int d, int l, int t, int w, int h) {
disposal_method = d; left = (WORD)l; top = (WORD)t; width = (WORD)w; height = (WORD)h;
}
int disposal_method;
WORD left, top, width, height;
src/Source/FreeImage/PluginGIF.cpp view on Meta::CPAN
throw FI_MSG_ERROR_MAGIC_NUMBER;
}
io->seek_proc(handle, 6, SEEK_CUR);
//Logical Screen Descriptor
io->seek_proc(handle, 4, SEEK_CUR);
BYTE packed;
if( io->read_proc(&packed, 1, 1, handle) < 1 ) {
throw "EOF reading Logical Screen Descriptor";
}
if( io->read_proc(&info->background_color, 1, 1, handle) < 1 ) {
throw "EOF reading Logical Screen Descriptor";
}
io->seek_proc(handle, 1, SEEK_CUR);
//Global Color Table
if( packed & GIF_PACKED_LSD_HAVEGCT ) {
info->global_color_table_offset = io->tell_proc(handle);
info->global_color_table_size = 2 << (packed & GIF_PACKED_LSD_GCTSIZE);
io->seek_proc(handle, 3 * info->global_color_table_size, SEEK_CUR);
}
src/Source/FreeImage/PluginGIF.cpp view on Meta::CPAN
if( (flags & GIF_PLAYBACK) == GIF_PLAYBACK ) {
//Logical Screen Descriptor
io->seek_proc(handle, 6, SEEK_SET);
WORD logicalwidth, logicalheight;
io->read_proc(&logicalwidth, 2, 1, handle);
io->read_proc(&logicalheight, 2, 1, handle);
#ifdef FREEIMAGE_BIGENDIAN
SwapShort(&logicalwidth);
SwapShort(&logicalheight);
#endif
//set the background color with 0 alpha
RGBQUAD background;
if( info->global_color_table_offset != 0 && info->background_color < info->global_color_table_size ) {
io->seek_proc(handle, (long)(info->global_color_table_offset + (info->background_color * 3)), SEEK_SET);
io->read_proc(&background.rgbRed, 1, 1, handle);
io->read_proc(&background.rgbGreen, 1, 1, handle);
io->read_proc(&background.rgbBlue, 1, 1, handle);
} else {
background.rgbRed = 0;
background.rgbGreen = 0;
background.rgbBlue = 0;
}
background.rgbReserved = 0;
//allocate entire logical area
dib = FreeImage_Allocate(logicalwidth, logicalheight, 32);
if( dib == NULL ) {
throw FI_MSG_ERROR_DIB_MEMORY;
}
//fill with background color to start
int x, y;
RGBQUAD *scanline;
for( y = 0; y < logicalheight; y++ ) {
scanline = (RGBQUAD *)FreeImage_GetScanLine(dib, y);
for( x = 0; x < logicalwidth; x++ ) {
*scanline++ = background;
}
}
//cache some info about each of the pages so we can avoid decoding as many of them as possible
std::vector<PageInfo> pageinfo;
int start = page, end = page;
while( start >= 0 ) {
//Graphic Control Extension
io->seek_proc(handle, (long)(info->graphic_control_extension_offsets[start] + 1), SEEK_SET);
io->read_proc(&packed, 1, 1, handle);
src/Source/FreeImage/PluginGIF.cpp view on Meta::CPAN
continue;
}
if( info.disposal_method == GIF_DISPOSAL_BACKGROUND ) {
for( y = 0; y < info.height; y++ ) {
const int scanidx = logicalheight - (y + info.top) - 1;
if ( scanidx < 0 ) {
break; // If data is corrupt, don't calculate in invalid scanline
}
scanline = (RGBQUAD *)FreeImage_GetScanLine(dib, scanidx) + info.left;
for( x = 0; x < info.width; x++ ) {
*scanline++ = background;
}
}
continue;
}
}
//decode page
FIBITMAP *pagedib = Load(io, handle, page, GIF_LOAD256, data);
if( pagedib != NULL ) {
RGBQUAD *pal = FreeImage_GetPalette(pagedib);
src/Source/FreeImage/PluginGIF.cpp view on Meta::CPAN
io->seek_proc(handle, (long)info->global_color_table_offset, SEEK_SET);
int i = 0;
while( i < info->global_color_table_size ) {
io->read_proc(&globalpalette[i].rgbRed, 1, 1, handle);
io->read_proc(&globalpalette[i].rgbGreen, 1, 1, handle);
io->read_proc(&globalpalette[i].rgbBlue, 1, 1, handle);
globalpalette[i].rgbReserved = 0;
i++;
}
FreeImage_SetMetadataEx(FIMD_ANIMATION, dib, "GlobalPalette", ANIMTAG_GLOBALPALETTE, FIDT_PALETTE, info->global_color_table_size, info->global_color_table_size * 4, globalpalette);
//background color
if( info->background_color < info->global_color_table_size ) {
FreeImage_SetBackgroundColor(dib, &globalpalette[info->background_color]);
}
}
//Application Extension
LONG loop = 1; //If no AE with a loop count is found, the default must be 1
for( idx = 0; idx < info->application_extension_offsets.size(); idx++ ) {
io->seek_proc(handle, (long)info->application_extension_offsets[idx], SEEK_SET);
io->read_proc(&b, 1, 1, handle);
if( b == 11 ) { //All AEs start with an 11 byte sub-block to determine what type of AE it is
char buf[11];
src/Source/FreeImage/PluginGIF.cpp view on Meta::CPAN
if( globalpalette_size >= 2 ) {
globalpalette = (RGBQUAD *)FreeImage_GetTagValue(tag);
}
}
//Logical Screen Descriptor
io->write_proc(&logicalwidth, 2, 1, handle);
io->write_proc(&logicalheight, 2, 1, handle);
packed = GIF_PACKED_LSD_COLORRES;
b = 0;
RGBQUAD background_color;
if( globalpalette != NULL ) {
packed |= GIF_PACKED_LSD_HAVEGCT;
if( globalpalette_size < 4 ) {
globalpalette_size = 2;
packed |= 0 & GIF_PACKED_LSD_GCTSIZE;
} else if( globalpalette_size < 8 ) {
globalpalette_size = 4;
packed |= 1 & GIF_PACKED_LSD_GCTSIZE;
} else if( globalpalette_size < 16 ) {
globalpalette_size = 8;
src/Source/FreeImage/PluginGIF.cpp view on Meta::CPAN
} else if( globalpalette_size < 128 ) {
globalpalette_size = 64;
packed |= 5 & GIF_PACKED_LSD_GCTSIZE;
} else if( globalpalette_size < 256 ) {
globalpalette_size = 128;
packed |= 6 & GIF_PACKED_LSD_GCTSIZE;
} else {
globalpalette_size = 256;
packed |= 7 & GIF_PACKED_LSD_GCTSIZE;
}
if( FreeImage_GetBackgroundColor(dib, &background_color) ) {
for( int i = 0; i < globalpalette_size; i++ ) {
if( background_color.rgbRed == globalpalette[i].rgbRed &&
background_color.rgbGreen == globalpalette[i].rgbGreen &&
background_color.rgbBlue == globalpalette[i].rgbBlue ) {
b = (BYTE)i;
break;
}
}
}
} else {
packed |= (bpp - 1) & GIF_PACKED_LSD_GCTSIZE;
}
io->write_proc(&packed, 1, 1, handle);
src/Source/FreeImage/PluginKOALA.cpp view on Meta::CPAN
#ifdef _WIN32
#pragma pack(push, 1)
#else
#pragma pack(1)
#endif
typedef struct tagKOALA {
BYTE image[8000]; // pixmap image
BYTE colour1[1000]; // first colourmap (colour 1 and 2)
BYTE colour2[1000]; // second colourmap (colour 3)
BYTE background; // background colour
} koala_t;
struct colour_t {
int r;
int g;
int b;
};
#ifdef _WIN32
#pragma pack(pop)
src/Source/FreeImage/PluginKOALA.cpp view on Meta::CPAN
// Get value of pixel at (x,y)
index = (x / 4) * 8 + (y % 8) + (y / 8) * CBM_WIDTH;
colourindex = (x / 4) + (y / 8) * 40;
pixel = (image.image[index] & pixel_mask[x % 4]) >> pixel_displacement[x % 4];
// Retrieve RGB values
switch (pixel) {
case 0: // Background
found_color = image.background;
break;
case 1: // Colour 1
found_color = image.colour1[colourindex] >> 4;
break;
case 2: // Colour 2
found_color = image.colour1[colourindex] & 0xf;
break;
src/Source/FreeImage/PluginPICT.cpp view on Meta::CPAN
// for reserved opcodes
#define res(length) { "reserved", (length), "reserved for Apple use" }
#define RGB_LEN 6
#define WORD_LEN -1
#define NA 0
static OpDef optable[] =
{
/* 0x00 */ { "NOP", 0, "nop" },
/* 0x01 */ { "Clip", NA, "clip" },
/* 0x02 */ { "BkPat", 8, "background pattern" },
/* 0x03 */ { "TxFont", 2, "text font (word)" },
/* 0x04 */ { "TxFace", 1, "text face (byte)" },
/* 0x05 */ { "TxMode", 2, "text mode (word)" },
/* 0x06 */ { "SpExtra", 4, "space extra (fixed point)" },
/* 0x07 */ { "PnSize", 4, "pen size (point)" },
/* 0x08 */ { "PnMode", 2, "pen mode (word)" },
/* 0x09 */ { "PnPat", 8, "pen pattern" },
/* 0x0a */ { "FillPat", 8, "fill pattern" },
/* 0x0b */ { "OvSize", 4, "oval size (point)" },
/* 0x0c */ { "Origin", 4, "dh, dv (word)" },
/* 0x0d */ { "TxSize", 2, "text size (word)" },
/* 0x0e */ { "FgColor", 4, "foreground color (longword)" },
/* 0x0f */ { "BkColor", 4, "background color (longword)" },
/* 0x10 */ { "TxRatio", 8, "numerator (point), denominator (point)" },
/* 0x11 */ { "Version", 1, "version (byte)" },
/* 0x12 */ { "BkPixPat", NA, "color background pattern" },
/* 0x13 */ { "PnPixPat", NA, "color pen pattern" },
/* 0x14 */ { "FillPixPat", NA, "color fill pattern" },
/* 0x15 */ { "PnLocHFrac", 2, "fractional pen position" },
/* 0x16 */ { "ChExtra", 2, "extra for each character" },
/* 0x17 */ res(0),
/* 0x18 */ res(0),
/* 0x19 */ res(0),
/* 0x1a */ { "RGBFgCol", RGB_LEN, "RGB foreColor" },
/* 0x1b */ { "RGBBkCol", RGB_LEN, "RGB backColor" },
/* 0x1c */ { "HiliteMode", 0, "hilite mode flag" },
src/Source/FreeImage/PluginPNG.cpp view on Meta::CPAN
else if ((trans_alpha) && (pixel_depth <= 8)) {
FreeImage_SetTransparencyTable(dib, (BYTE *)trans_alpha, num_trans);
}
} else if((color_type == PNG_COLOR_TYPE_PALETTE) && trans_alpha) {
// transparency table
FreeImage_SetTransparencyTable(dib, (BYTE *)trans_alpha, num_trans);
}
}
// store the background color (only supported for FIT_BITMAP types)
if ((image_type == FIT_BITMAP) && png_get_valid(png_ptr, info_ptr, PNG_INFO_bKGD)) {
// Get the background color to draw transparent and alpha images over.
// Note that even if the PNG file supplies a background, you are not required to
// use it - you should use the (solid) application background if it has one.
png_color_16p image_background = NULL;
RGBQUAD rgbBkColor;
if (png_get_bKGD(png_ptr, info_ptr, &image_background)) {
rgbBkColor.rgbRed = (BYTE)image_background->red;
rgbBkColor.rgbGreen = (BYTE)image_background->green;
rgbBkColor.rgbBlue = (BYTE)image_background->blue;
rgbBkColor.rgbReserved = 0;
FreeImage_SetBackgroundColor(dib, &rgbBkColor);
}
}
// get physical resolution
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_pHYs)) {
png_uint_32 res_x, res_y;
src/Source/FreeImage/PluginPNG.cpp view on Meta::CPAN
// Optional gamma chunk is strongly suggested if you have any guess
// as to the correct gamma of the image.
// png_set_gAMA(png_ptr, info_ptr, gamma);
// set the transparency table
if (bIsTransparent) {
png_set_tRNS(png_ptr, info_ptr, FreeImage_GetTransparencyTable(dib), FreeImage_GetTransparencyCount(dib), NULL);
}
// set the background color
if(FreeImage_HasBackgroundColor(dib)) {
png_color_16 image_background;
RGBQUAD rgbBkColor;
FreeImage_GetBackgroundColor(dib, &rgbBkColor);
memset(&image_background, 0, sizeof(png_color_16));
image_background.blue = rgbBkColor.rgbBlue;
image_background.green = rgbBkColor.rgbGreen;
image_background.red = rgbBkColor.rgbRed;
image_background.index = rgbBkColor.rgbReserved;
png_set_bKGD(png_ptr, info_ptr, &image_background);
}
// Write the file header information.
png_write_info(png_ptr, info_ptr);
// write out the image data
#ifndef FREEIMAGE_BIGENDIAN
if (bit_depth == 16) {
src/Source/FreeImageToolkit/Background.cpp view on Meta::CPAN
if (m == 0) {
break;
}
}
palette += sizeof(RGBQUAD);
}
}
return result;
}
/** @brief Blends an alpha-transparent foreground color over an opaque background
color.
This function blends the alpha-transparent foreground color fgcolor over the
background color bgcolor. The background color is considered fully opaque,
whatever it's alpha value contains, whereas the foreground color is considered
to be a real RGBA color with an alpha value, which is used for the blend
operation. The resulting color is returned through the blended parameter.
@param bgcolor The background color for the blend operation.
@param fgcolor The foreground color for the blend operation. This color's alpha
value, stored in the rgbReserved member, is the alpha value used for the blend
operation.
@param blended This out parameter takes the blended color and so, returns it to
the caller. This color's alpha value will be 0xFF (255) so, the blended color
itself has no transparency. The this argument is not changed, if the function
fails.
@return Returns TRUE on success, FALSE otherwise. This function fails if any of
the color arguments is a null pointer.
*/
src/Source/FreeImageToolkit/Background.cpp view on Meta::CPAN
if (supports_alpha && (options & FI_COLOR_IS_RGBA_COLOR)) {
if (color->rgbReserved == 0) {
// the fill color is fully transparent; we are done
return TRUE;
}
// Only if the fill color is NOT fully opaque, draw it with
// the (much) slower FreeImage_DrawLine function and return.
// Since we do not have the FreeImage_DrawLine function in this
// release, just assume to have an unicolor background and fill
// all with an 'alpha-blended' color.
if (color->rgbReserved < 255) {
// If we will draw on an unicolor background, it's
// faster to draw opaque with an alpha blended color.
// So, first get the color from the first pixel in the
// image (bottom-left pixel).
RGBQUAD bgcolor;
if (bpp == 8) {
bgcolor = FreeImage_GetPalette(dib)[*src_bits];
} else {
bgcolor.rgbBlue = src_bits[FI_RGBA_BLUE];
bgcolor.rgbGreen = src_bits[FI_RGBA_GREEN];
bgcolor.rgbRed = src_bits[FI_RGBA_RED];
src/Source/FreeImageToolkit/Background.cpp view on Meta::CPAN
which uses 4 bytes.
So, color must point to a double, if the image to be filled is of type FIT_DOUBLE and
point to a RGBF structure if the image is of type FIT_RGBF and so on.
However, the fill color is always specified through a RGBQUAD structure for all images
of type FIT_BITMAP. So, for 32- and 24-bit images, the red, green and blue members of
the RGBQUAD structure are directly used for the image's red, green and blue channel
respectively. Although alpha transparent RGBQUAD colors are supported, the alpha channel
of a 32-bit image never gets modified by this function. A fill color with an alpha value
smaller than 255 gets blended with the image's actual background color, which is determined
from the image's bottom-left pixel. So, currently using alpha enabled colors, assumes the
image to be unicolor before the fill operation. However, the RGBQUAD's rgbReserved member is
only taken into account, if option FI_COLOR_IS_RGBA_COLOR has been specified.
For 16-bit images, the red-, green- and blue components of the specified color are
transparently translated into either the 16-bit 555 or 565 representation. This depends
on the image's actual red- green- and blue masks.
Special attention must be payed for palletized images. Generally, the RGB color specified
is looked up in the image's palette. The found palette index is then used to fill the image.
src/Source/FreeImageToolkit/Background.cpp view on Meta::CPAN
memcpy(dst_bits, src_bits, bytes);
dst_bits += pitch;
}
return TRUE;
}
/** @brief Allocates a new image of the specified type, width, height and bit depth and
optionally fills it with the specified color.
This function is an extension to FreeImage_AllocateT, which additionally supports specifying
a palette to be set for the newly create image, as well as specifying a background color,
the newly created image should initially be filled with.
Basically, this function internally relies on function FreeImage_AllocateT, followed by a
call to FreeImage_FillBackground. This is why both parameters color and options behave the
same as it is documented for function FreeImage_FillBackground. So, please refer to the
documentation of FreeImage_FillBackground to learn more about parameters color and options.
The palette specified through parameter palette is only copied to the newly created
image, if its image type is FIT_BITMAP and the desired bit depth is smaller than or equal
to 8 bits per pixel. In other words, the palette parameter is only taken into account for
palletized images. However, if the preceding conditions match and if palette is not NULL,
the memory pointed to by the palette pointer is assumed to be at least as large as size
of a fully populated palette for the desired bit depth. So, for an 8-bit image, this size
is 256 x sizeof(RGBQUAD), for an 4-bit image it is 16 x sizeof(RGBQUAD) and it is
2 x sizeof(RGBQUAD) for a 1-bit image. In other words, this function does not support
partial palettes.
However, specifying a palette is not necessarily needed, even for palletized images. This
function is capable of implicitly creating a palette, if parameter palette is NULL. If the
specified background color is a greyscale value (red = green = blue) or if option
FI_COLOR_ALPHA_IS_INDEX is specified, a greyscale palette is created. For a 1-bit image, only
if the specified background color is either black or white, a monochrome palette, consisting
of black and white only is created. In any case, the darker colors are stored at the smaller
palette indices.
If the specified background color is not a greyscale value, or is neither black nor white
for a 1-bit image, solely this single color is injected into the otherwise black-initialized
palette. For this operation, option FI_COLOR_ALPHA_IS_INDEX is implicit, so the specified
color is applied to the palette entry, specified by the background color's rgbReserved
member. The image is then filled with this palette index.
This function returns a newly created image as function FreeImage_AllocateT does, if both
parameters color and palette are NULL. If only color is NULL, the palette pointed to by
parameter palette is initially set for the new image, if a palletized image of type
FIT_BITMAP is created. However, in the latter case, this function returns an image, whose
pixels are all initialized with zeros so, the image will be filled with the color of the
first palette entry.
@param type Specifies the image type of the new image.
src/Source/FreeImageToolkit/Background.cpp view on Meta::CPAN
}
}
}
return bitmap;
}
/** @brief Allocates a new image of the specified width, height and bit depth and optionally
fills it with the specified color.
This function is an extension to FreeImage_Allocate, which additionally supports specifying
a palette to be set for the newly create image, as well as specifying a background color,
the newly created image should initially be filled with.
Basically, this function internally relies on function FreeImage_Allocate, followed by a
call to FreeImage_FillBackground. This is why both parameters color and options behave the
same as it is documented for function FreeImage_FillBackground. So, please refer to the
documentation of FreeImage_FillBackground to learn more about parameters color and options.
The palette specified through parameter palette is only copied to the newly created
image, if the desired bit depth is smaller than or equal to 8 bits per pixel. In other words,
the palette parameter is only taken into account for palletized images. However, if the
image to be created is a palletized image and if palette is not NULL, the memory pointed to
by the palette pointer is assumed to be at least as large as size of a fully populated
palette for the desired bit depth. So, for an 8-bit image, this size is 256 x sizeof(RGBQUAD),
for an 4-bit image it is 16 x sizeof(RGBQUAD) and it is 2 x sizeof(RGBQUAD) for a 1-bit
image. In other words, this function does not support partial palettes.
However, specifying a palette is not necessarily needed, even for palletized images. This
function is capable of implicitly creating a palette, if parameter palette is NULL. If the
specified background color is a greyscale value (red = green = blue) or if option
FI_COLOR_ALPHA_IS_INDEX is specified, a greyscale palette is created. For a 1-bit image, only
if the specified background color is either black or white, a monochrome palette, consisting
of black and white only is created. In any case, the darker colors are stored at the smaller
palette indices.
If the specified background color is not a greyscale value, or is neither black nor white
for a 1-bit image, solely this single color is injected into the otherwise black-initialized
palette. For this operation, option FI_COLOR_ALPHA_IS_INDEX is implicit, so the specified
color is applied to the palette entry, specified by the background color's rgbReserved
member. The image is then filled with this palette index.
This function returns a newly created image as function FreeImage_Allocate does, if both
parameters color and palette are NULL. If only color is NULL, the palette pointed to by
parameter palette is initially set for the new image, if a palletized image of type
FIT_BITMAP is created. However, in the latter case, this function returns an image, whose
pixels are all initialized with zeros so, the image will be filled with the color of the
first palette entry.
@param width The desired width in pixels of the new image.
src/Source/FreeImageToolkit/Background.cpp view on Meta::CPAN
@param green_mask Specifies the bits used to store the green components of a pixel.
@param blue_mask Specifies the bits used to store the blue components of a pixel.
@return Returns a pointer to a newly allocated image on success, NULL otherwise.
*/
FIBITMAP * DLL_CALLCONV
FreeImage_AllocateEx(int width, int height, int bpp, const RGBQUAD *color, int options, const RGBQUAD *palette, unsigned red_mask, unsigned green_mask, unsigned blue_mask) {
return FreeImage_AllocateExT(FIT_BITMAP, width, height, bpp, ((void *)color), options, palette, red_mask, green_mask, blue_mask);
}
/** @brief Enlarges or shrinks an image selectively per side and fills newly added areas
with the specified background color.
This function enlarges or shrinks an image selectively per side. The main purpose of this
function is to add borders to an image. To add a border to any of the image's sides, a
positive integer value must be passed in any of the parameters left, top, right or bottom.
This value represents the border's width in pixels. Newly created parts of the image (the
border areas) are filled with the specified color. Specifying a negative integer value for
a certain side, will shrink or crop the image on this side. Consequently, specifying zero
for a certain side will not change the image's extension on that side.
So, calling this function with all parameters left, top, right and bottom set to zero, is
src/Source/FreeImageToolkit/Background.cpp view on Meta::CPAN
dstPtr -= dstPitch;
}
}
// copy metadata from src to dst
FreeImage_CloneMetadata(dst, src);
// copy transparency table
FreeImage_SetTransparencyTable(dst, FreeImage_GetTransparencyTable(src), FreeImage_GetTransparencyCount(src));
// copy background color
RGBQUAD bkcolor;
if( FreeImage_GetBackgroundColor(src, &bkcolor) ) {
FreeImage_SetBackgroundColor(dst, &bkcolor);
}
// clone resolution
FreeImage_SetDotsPerMeterX(dst, FreeImage_GetDotsPerMeterX(src));
FreeImage_SetDotsPerMeterY(dst, FreeImage_GetDotsPerMeterY(src));
// clone ICC profile
src/Source/FreeImageToolkit/ClassicRotate.cpp view on Meta::CPAN
*/
template <class T> void
HorizontalSkewT(FIBITMAP *src, FIBITMAP *dst, int row, int iOffset, double weight, const void *bkcolor = NULL) {
int iXPos;
const unsigned src_width = FreeImage_GetWidth(src);
const unsigned dst_width = FreeImage_GetWidth(dst);
T pxlSrc[4], pxlLeft[4], pxlOldLeft[4]; // 4 = 4*sizeof(T) max
// background
const T pxlBlack[4] = {0, 0, 0, 0 };
const T *pxlBkg = static_cast<const T*>(bkcolor); // assume at least bytespp and 4*sizeof(T) max
if(!pxlBkg) {
// default background color is black
pxlBkg = pxlBlack;
}
// calculate the number of bytes per pixel
const unsigned bytespp = FreeImage_GetLine(src) / FreeImage_GetWidth(src);
// calculate the number of samples per pixel
const unsigned samples = bytespp / sizeof(T);
BYTE *src_bits = FreeImage_GetScanLine(src, row);
BYTE *dst_bits = FreeImage_GetScanLine(dst, row);
// fill gap left of skew with background
if(bkcolor) {
for(int k = 0; k < iOffset; k++) {
memcpy(&dst_bits[k * bytespp], bkcolor, bytespp);
}
AssignPixel((BYTE*)&pxlOldLeft[0], (BYTE*)bkcolor, bytespp);
} else {
if(iOffset > 0) {
memset(dst_bits, 0, iOffset * bytespp);
}
memset(&pxlOldLeft[0], 0, bytespp);
src/Source/FreeImageToolkit/ClassicRotate.cpp view on Meta::CPAN
// go to rightmost point of skew
iXPos = src_width + iOffset;
if((iXPos >= 0) && (iXPos < (int)dst_width)) {
dst_bits = FreeImage_GetScanLine(dst, row) + iXPos * bytespp;
// If still in image bounds, put leftovers there
AssignPixel((BYTE*)dst_bits, (BYTE*)&pxlOldLeft[0], bytespp);
// clear to the right of the skewed line with background
dst_bits += bytespp;
if(bkcolor) {
for(unsigned i = 0; i < dst_width - iXPos - 1; i++) {
memcpy(&dst_bits[i * bytespp], bkcolor, bytespp);
}
} else {
memset(dst_bits, 0, bytespp * (dst_width - iXPos - 1));
}
}
src/Source/FreeImageToolkit/ClassicRotate.cpp view on Meta::CPAN
*/
template <class T> void
VerticalSkewT(FIBITMAP *src, FIBITMAP *dst, int col, int iOffset, double weight, const void *bkcolor = NULL) {
int iYPos;
unsigned src_height = FreeImage_GetHeight(src);
unsigned dst_height = FreeImage_GetHeight(dst);
T pxlSrc[4], pxlLeft[4], pxlOldLeft[4]; // 4 = 4*sizeof(T) max
// background
const T pxlBlack[4] = {0, 0, 0, 0 };
const T *pxlBkg = static_cast<const T*>(bkcolor); // assume at least bytespp and 4*sizeof(T) max
if(!pxlBkg) {
// default background color is black
pxlBkg = pxlBlack;
}
// calculate the number of bytes per pixel
const unsigned bytespp = FreeImage_GetLine(src) / FreeImage_GetWidth(src);
// calculate the number of samples per pixel
const unsigned samples = bytespp / sizeof(T);
const unsigned src_pitch = FreeImage_GetPitch(src);
const unsigned dst_pitch = FreeImage_GetPitch(dst);
const unsigned index = col * bytespp;
BYTE *src_bits = FreeImage_GetBits(src) + index;
BYTE *dst_bits = FreeImage_GetBits(dst) + index;
// fill gap above skew with background
if(bkcolor) {
for(int k = 0; k < iOffset; k++) {
memcpy(dst_bits, bkcolor, bytespp);
dst_bits += dst_pitch;
}
memcpy(&pxlOldLeft[0], bkcolor, bytespp);
} else {
for(int k = 0; k < iOffset; k++) {
memset(dst_bits, 0, bytespp);
dst_bits += dst_pitch;
src/Source/FreeImageToolkit/ClassicRotate.cpp view on Meta::CPAN
}
// go to bottom point of skew
iYPos = src_height + iOffset;
if((iYPos >= 0) && (iYPos < (int)dst_height)) {
dst_bits = FreeImage_GetScanLine(dst, iYPos) + index;
// if still in image bounds, put leftovers there
AssignPixel((BYTE*)(dst_bits), (BYTE*)(&pxlOldLeft[0]), bytespp);
// clear below skewed line with background
if(bkcolor) {
while(++iYPos < (int)dst_height) {
dst_bits += dst_pitch;
AssignPixel((BYTE*)(dst_bits), (BYTE*)(bkcolor), bytespp);
}
} else {
while(++iYPos < (int)dst_height) {
dst_bits += dst_pitch;
memset(dst_bits, 0, bytespp);
}
src/Source/FreeImageToolkit/ClassicRotate.cpp view on Meta::CPAN
if(bpp == 8) {
// copy original palette to rotated bitmap
RGBQUAD *src_pal = FreeImage_GetPalette(dib);
RGBQUAD *dst_pal = FreeImage_GetPalette(dst);
memcpy(&dst_pal[0], &src_pal[0], 256 * sizeof(RGBQUAD));
// copy transparency table
FreeImage_SetTransparencyTable(dst, FreeImage_GetTransparencyTable(dib), FreeImage_GetTransparencyCount(dib));
// copy background color
RGBQUAD bkcolor;
if( FreeImage_GetBackgroundColor(dib, &bkcolor) ) {
FreeImage_SetBackgroundColor(dst, &bkcolor);
}
}
// copy metadata from src to dst
FreeImage_CloneMetadata(dst, dib);
src/Source/FreeImageToolkit/CopyPaste.cpp view on Meta::CPAN
memcpy(dst_bits + (y * dst_pitch), src_bits + (y * src_pitch), dst_line);
}
}
// copy metadata from src to dst
FreeImage_CloneMetadata(dst, src);
// copy transparency table
FreeImage_SetTransparencyTable(dst, FreeImage_GetTransparencyTable(src), FreeImage_GetTransparencyCount(src));
// copy background color
RGBQUAD bkcolor;
if( FreeImage_GetBackgroundColor(src, &bkcolor) ) {
FreeImage_SetBackgroundColor(dst, &bkcolor);
}
// clone resolution
FreeImage_SetDotsPerMeterX(dst, FreeImage_GetDotsPerMeterX(src));
FreeImage_SetDotsPerMeterY(dst, FreeImage_GetDotsPerMeterY(src));
// clone ICC profile
src/Source/FreeImageToolkit/CopyPaste.cpp view on Meta::CPAN
bitmap. All FreeImage operations, like saving, displaying and all the
toolkit functions, when applied to the view, only affect the view's
rectangular area.
Although the view's backing image's bits not need to be copied around,
which makes the view much faster than similar solutions using
FreeImage_Copy, a view uses some private memory that needs to be freed by
calling FreeImage_Unload on the view's handle to prevent memory leaks.
Only the backing image's pixels are shared by the view. For all other image
data, notably for the resolution, background color, color palette,
transparency table and for the ICC profile, the view gets a private copy
of the data. By default, the backing image's metadata is NOT copied to
the view.
As with all FreeImage functions that take a rectangle region, top and left
positions are included, whereas right and bottom positions are excluded
from the rectangle area.
Since the memory block shared by the backing image and the view must start
at a byte boundary, the value of parameter left must be a multiple of 8
src/Source/FreeImageToolkit/CopyPaste.cpp view on Meta::CPAN
if (dst == NULL) {
return NULL;
}
// copy some basic image properties needed for displaying and saving
// resolution
FreeImage_SetDotsPerMeterX(dst, FreeImage_GetDotsPerMeterX(dib));
FreeImage_SetDotsPerMeterY(dst, FreeImage_GetDotsPerMeterY(dib));
// background color
RGBQUAD bkcolor;
if (FreeImage_GetBackgroundColor(dib, &bkcolor)) {
FreeImage_SetBackgroundColor(dst, &bkcolor);
}
// palette
memcpy(FreeImage_GetPalette(dst), FreeImage_GetPalette(dib), FreeImage_GetColorsUsed(dib) * sizeof(RGBQUAD));
// transparency table
FreeImage_SetTransparencyTable(dst, FreeImage_GetTransparencyTable(dib), FreeImage_GetTransparencyCount(dib));
src/Source/FreeImageToolkit/Display.cpp view on Meta::CPAN
// THIS DISCLAIMER.
//
// Use at your own risk!
// ==========================================================
#include "FreeImage.h"
#include "Utilities.h"
/**
@brief Composite a foreground image against a background color or a background image.
The equation for computing a composited sample value is:<br>
output = alpha * foreground + (1-alpha) * background<br>
where alpha and the input and output sample values are expressed as fractions in the range 0 to 1.
For colour images, the computation is done separately for R, G, and B samples.
@param fg Foreground image
@param useFileBkg If TRUE and a file background is present, use it as the background color
@param appBkColor If not equal to NULL, and useFileBkg is FALSE, use this color as the background color
@param bg If not equal to NULL and useFileBkg is FALSE and appBkColor is NULL, use this as the background image
@return Returns the composite image if successful, returns NULL otherwise
@see FreeImage_IsTransparent, FreeImage_HasBackgroundColor
*/
FIBITMAP * DLL_CALLCONV
FreeImage_Composite(FIBITMAP *fg, BOOL useFileBkg, RGBQUAD *appBkColor, FIBITMAP *bg) {
if(!FreeImage_HasPixels(fg)) return NULL;
int width = FreeImage_GetWidth(fg);
int height = FreeImage_GetHeight(fg);
int bpp = FreeImage_GetBPP(fg);
src/Source/FreeImageToolkit/Display.cpp view on Meta::CPAN
return NULL;
}
int bytespp = (bpp == 8) ? 1 : 4;
int x, y, c;
BYTE alpha = 0, not_alpha;
BYTE index;
RGBQUAD fgc; // foreground color
RGBQUAD bkc; // background color
memset(&fgc, 0, sizeof(RGBQUAD));
memset(&bkc, 0, sizeof(RGBQUAD));
// allocate the composite image
FIBITMAP *composite = FreeImage_Allocate(width, height, 24, FI_RGBA_RED_MASK, FI_RGBA_GREEN_MASK, FI_RGBA_BLUE_MASK);
if(!composite) return NULL;
// get the palette
RGBQUAD *pal = FreeImage_GetPalette(fg);
// retrieve the alpha table from the foreground image
BOOL bIsTransparent = FreeImage_IsTransparent(fg);
BYTE *trns = FreeImage_GetTransparencyTable(fg);
// retrieve the background color from the foreground image
BOOL bHasBkColor = FALSE;
if(useFileBkg && FreeImage_HasBackgroundColor(fg)) {
FreeImage_GetBackgroundColor(fg, &bkc);
bHasBkColor = TRUE;
} else {
// no file background color
// use application background color ?
if(appBkColor) {
memcpy(&bkc, appBkColor, sizeof(RGBQUAD));
bHasBkColor = TRUE;
}
// use background image ?
else if(bg) {
bHasBkColor = FALSE;
}
}
for(y = 0; y < height; y++) {
// foreground
BYTE *fg_bits = FreeImage_GetScanLine(fg, y);
// background
BYTE *bg_bits = FreeImage_GetScanLine(bg, y);
// composite image
BYTE *cp_bits = FreeImage_GetScanLine(composite, y);
for(x = 0; x < width; x++) {
// foreground color + alpha
if(bpp == 8) {
// get the foreground color
src/Source/FreeImageToolkit/Display.cpp view on Meta::CPAN
}
else if(bpp == 32) {
// get the foreground color
fgc.rgbBlue = fg_bits[FI_RGBA_BLUE];
fgc.rgbGreen = fg_bits[FI_RGBA_GREEN];
fgc.rgbRed = fg_bits[FI_RGBA_RED];
// get the alpha
alpha = fg_bits[FI_RGBA_ALPHA];
}
// background color
if(!bHasBkColor) {
if(bg) {
// get the background color from the background image
bkc.rgbBlue = bg_bits[FI_RGBA_BLUE];
bkc.rgbGreen = bg_bits[FI_RGBA_GREEN];
bkc.rgbRed = bg_bits[FI_RGBA_RED];
}
else {
// use a checkerboard pattern
c = (((y & 0x8) == 0) ^ ((x & 0x8) == 0)) * 192;
c = c ? c : 255;
bkc.rgbBlue = (BYTE)c;
bkc.rgbGreen = (BYTE)c;
bkc.rgbRed = (BYTE)c;
}
}
// composition
if(alpha == 0) {
// output = background
cp_bits[FI_RGBA_BLUE] = bkc.rgbBlue;
cp_bits[FI_RGBA_GREEN] = bkc.rgbGreen;
cp_bits[FI_RGBA_RED] = bkc.rgbRed;
}
else if(alpha == 255) {
// output = foreground
cp_bits[FI_RGBA_BLUE] = fgc.rgbBlue;
cp_bits[FI_RGBA_GREEN] = fgc.rgbGreen;
cp_bits[FI_RGBA_RED] = fgc.rgbRed;
}
else {
// output = alpha * foreground + (1-alpha) * background
not_alpha = (BYTE)~alpha;
cp_bits[FI_RGBA_BLUE] = (BYTE)((alpha * (WORD)fgc.rgbBlue + not_alpha * (WORD)bkc.rgbBlue) >> 8);
cp_bits[FI_RGBA_GREEN] = (BYTE)((alpha * (WORD)fgc.rgbGreen + not_alpha * (WORD)bkc.rgbGreen) >> 8);
cp_bits[FI_RGBA_RED] = (BYTE)((alpha * (WORD)fgc.rgbRed + not_alpha * (WORD)bkc.rgbRed) >> 8);
}
fg_bits += bytespp;
bg_bits += 3;
cp_bits += 3;
}
src/Source/LibPNG/CHANGES view on Meta::CPAN
png_create_info_struct(), png_destroy_read_struct(), and
png_destroy_write_struct() instead of the separate calls to
malloc and png_read_init(), png_info_init(), and png_write_init()
Changed warning/error callback functions to fix bug - this means you
should use the new initialization API if you were using the old
png_set_message_fn() calls, and that the old API no longer exists
so that people are aware that they need to change their code
Changed filter selection API to allow selection of multiple filters
since it didn't work in previous versions of libpng anyways
Optimized filter selection code
Fixed png_set_background() to allow using an arbitrary RGB color for
paletted images
Fixed gamma and background correction for paletted images, so
png_correct_palette is not needed unless you are correcting an
external palette (you will need to #define PNG_CORRECT_PALETTE_SUPPORTED
in pngconf.h) - if nobody uses this, it may disappear in the future.
Fixed bug with Borland 64K memory allocation (Alexander Lehmann)
Fixed bug in interlace handling (Smarasderagd, I think)
Added more error checking for writing and image to reduce invalid files
Separated read and write functions so that they won't both be linked
into a binary when only reading or writing functionality is used
New pngtest image also has interlacing and zTXt
Updated documentation to reflect new API
Version 0.90 [January, 1997]
Made CRC errors/warnings on critical and ancillary chunks configurable
libpng will use the zlib CRC routines by (compile-time) default
Changed DOS small/medium model memory support - needs zlib 1.04 (Tim Wegner)
Added external C++ wrapper statements to png.h (Gilles Dauphin)
Allow PNG file to be read when some or all of file signature has already
been read from the beginning of the stream. ****This affects the size
of info_struct and invalidates all programs that use a shared libpng****
Fixed png_filler() declarations
Fixed? background color conversions
Fixed order of error function pointers to match documentation
Current chunk name is now available in png_struct to reduce the number
of nearly identical error messages (will simplify multi-lingual
support when available)
Try to get ready for unknown-chunk callback functions:
- previously read critical chunks are flagged, so the chunk handling
routines can determine if the chunk is in the right place
- all chunk handling routines have the same prototypes, so we will
be able to handle all chunks via a callback mechanism
Try to fix Linux "setjmp" buffer size problems
src/Source/LibPNG/CHANGES view on Meta::CPAN
Fixed bug in gamma handling of 4-bit grayscale
Added 2-bit grayscale gamma handling (Glenn R-P)
Added more typecasts. 65536L becomes (png_uint_32)65536L, etc. (Glenn R-P)
Minor corrections in libpng.txt
Added simple sRGB support (Glenn R-P)
Easier conditional compiling, e.g.,
define PNG_READ/WRITE_NOT_FULLY_SUPPORTED;
all configurable options can be selected from command-line instead
of having to edit pngconf.h (Glenn R-P)
Fixed memory leak in pngwrite.c (free info_ptr->text) (Glenn R-P)
Added more conditions for png_do_background, to avoid changing
black pixels to background when a background is supplied and
no pixels are transparent
Repaired PNG_NO_STDIO behavior
Tested NODIV support and made it default behavior (Greg Roelofs)
Added "-m" option and PNGTEST_DEBUG_MEMORY to pngtest (John Bowler)
Regularized version numbering scheme and bumped shared-library major
version number to 2 to avoid problems with libpng 0.89 apps
(Greg Roelofs)
Version 0.98 [January, 1998]
Cleaned up some typos in libpng.txt and in code documentation
src/Source/LibPNG/CHANGES view on Meta::CPAN
Updated some of the makefiles (Tom Lane)
Changed some typedefs (s_start, etc.) in pngrutil.c
Fixed dimensions of "short_months" array in pngwrite.c
Replaced ansi2knr.c with the one from jpeg-v6
Version 1.0.0 [March 8, 1998]
Changed name from 1.00 to 1.0.0 (Adam Costello)
Added smakefile.ppc (with SCOPTIONS.ppc) for Amiga PPC (Andreas Kleinert)
Version 1.0.0a [March 9, 1998]
Fixed three bugs in pngrtran.c to make gamma+background handling consistent
(Greg Roelofs)
Changed format of the PNG_LIBPNG_VER integer to xyyzz instead of xyz
for major, minor, and bugfix releases. This is 10001. (Adam Costello,
Tom Lane)
Make months range from 1-12 in png_convert_to_rfc1123
Version 1.0.0b [March 13, 1998]
Quieted compiler complaints about two empty "for" loops in pngrutil.c
Minor changes to makefile.s2x
Removed #ifdef/#endif around a png_free() in pngread.c
src/Source/LibPNG/CHANGES view on Meta::CPAN
Added pngdll.mak and pngdef.pas to scripts directory, contributed by
Bob Dellaca, to make a png32bd.dll with Borland C++ 4.5
Fixed error in example.c with png_set_text: num_text is 3, not 2 (Guido V.)
Changed several loops from count-down to count-up, for consistency.
Version 1.0.1e [June 6, 1998]
Revised libpng.txt and libpng.3 description of png_set_read|write_fn(), and
added warnings when people try to set png_read_fn and png_write_fn in
the same structure.
Added a test such that png_do_gamma will be done when num_trans==0
for truecolor images that have defined a background. This corrects an
error that was introduced in libpng-0.90 that can cause gamma processing
to be skipped.
Added tests in png.h to include "trans" and "trans_values" in structures
when PNG_READ_BACKGROUND_SUPPORTED or PNG_READ_EXPAND_SUPPORTED is defined.
Add png_free(png_ptr->time_buffer) in png_destroy_read_struct()
Moved png_convert_to_rfc_1123() from pngwrite.c to png.c
Added capability for user-provided malloc_fn() and free_fn() functions,
and revised pngtest.c to demonstrate their use, replacing the
PNGTEST_DEBUG_MEM feature.
Added makefile.w32, for Microsoft C++ 4.0 and later (Tim Wegner).
src/Source/LibPNG/CHANGES view on Meta::CPAN
Cosmetic changes in pngtest.c
Version 1.0.5q [February 5, 2000]
Relocated the makefile.solaris warning about PATH problems.
Fixed pngvcrd.c bug by pushing/popping registers in mmxsupport (Bruce Oberg)
Revised makefile.gcmmx
Added PNG_SETJMP_SUPPORTED, PNG_SETJMP_NOT_SUPPORTED, and PNG_ABORT() macros
Version 1.0.5r [February 7, 2000]
Removed superfluous prototype for png_get_itxt from png.h
Fixed a bug in pngrtran.c that improperly expanded the background color.
Return *num_text=0 from png_get_text() when appropriate, and fix documentation
of png_get_text() in libpng.txt/libpng.3.
Version 1.0.5s [February 18, 2000]
Added "png_jmp_env()" macro to pngconf.h, to help people migrate to the
new error handler that's planned for the next libpng release, and changed
example.c, pngtest.c, and contrib programs to use this macro.
Revised some of the DLL-export macros in pngconf.h (Greg Roelofs)
Fixed a bug in png_read_png() that caused it to fail to expand some images
that it should have expanded.
src/Source/LibPNG/CHANGES view on Meta::CPAN
Version 1.0.6f [April 14, 2000]
Revised png_set_iCCP() and png_set_rows() to avoid prematurely freeing data.
Add checks in png_set_text() for NULL members of the input text structure.
Revised libpng.txt/libpng.3.
Removed superfluous prototype for png_set_iTXt from png.h
Removed "else" from pngread.c, after png_error(), and changed "0" to "length".
Changed several png_errors about malformed ancillary chunks to png_warnings.
Version 1.0.6g [April 24, 2000]
Added png_pass-* arrays to pnggccrd.c when PNG_USE_LOCAL_ARRAYS is defined.
Relocated paragraph about png_set_background() in libpng.3/libpng.txt
and other revisions (Matthias Benckmann)
Relocated info_ptr->free_me, png_ptr->free_me, and other info_ptr and
png_ptr members to restore binary compatibility with libpng-1.0.5
(breaks compatibility with libpng-1.0.6).
Version 1.0.6h [April 24, 2000]
Changed shared library so-number pattern from 2.x.y.z to xy.z (this builds
libpng.so.10 & libpng.so.10.6h instead of libpng.so.2 & libpng.so.2.1.0.6h)
This is a temporary change for test purposes.
src/Source/LibPNG/CHANGES view on Meta::CPAN
Revised makefile.sgi and makefile.sggcc
Replaced calls to fprintf(stderr,...) with png_warning() in pnggccrd.c
Removed restriction that do_invert_mono only operate on 1-bit opaque files
Version 1.2.0 [September 1, 2001]
Changed a png_warning() to png_debug() in pnggccrd.c
Fixed contrib/gregbook/rpng-x.c, rpng2-x.c to avoid crash with XFreeGC().
Version 1.2.1beta1 [October 19, 2001]
Revised makefile.std in contrib/pngminus
Include background_1 in png_struct regardless of gamma support.
Revised makefile.netbsd and makefile.macosx, added makefile.darwin.
Revised example.c to provide more details about using row_callback().
Version 1.2.1beta2 [October 25, 2001]
Added type cast to each NULL appearing in a function call, except for
WINCE functions.
Added makefile.so9.
Version 1.2.1beta3 [October 27, 2001]
Removed type casts from all NULLs.
src/Source/LibPNG/CHANGES view on Meta::CPAN
Revised png_zalloc() so zlib handles errors (uses PNG_FLAG_MALLOC_NULL_MEM_OK)
Version 1.2.2beta2 [February 23, 2002]
Check chunk_length and idat_size for invalid (over PNG_MAX_UINT) lengths.
Check for invalid image dimensions in png_get_IHDR.
Added missing "fi;" in the install target of the SGI makefiles.
Added install-static to all makefiles that make shared libraries.
Always do gamma compensation when image is partially transparent.
Version 1.2.2beta3 [March 7, 2002]
Compute background.gray and background_1.gray even when color_type is RGB
in case image gets reduced to gray later.
Modified shared-library makefiles to install pkgconfig/libpngNN.pc.
Export (with PNGAPI) png_zalloc, png_zfree, and png_handle_as_unknown
Removed unused png_write_destroy_info prototype from png.h
Eliminated incorrect use of width_mmx from pnggccrd.c in pixel_bytes == 8 case
Added install-shared target to all makefiles that make shared libraries.
Stopped a double free of palette, hist, and trans when not using free_me.
Added makefile.32sunu for Sun Ultra 32 and makefile.64sunu for Sun Ultra 64.
Version 1.2.2beta4 [March 8, 2002]
Compute background.gray and background_1.gray even when color_type is RGB
in case image gets reduced to gray later (Jason Summers).
Relocated a misplaced /bin/rm in the "install-shared" makefile targets
Added PNG_1_0_X macro which can be used to build a 1.0.x-compatible library.
Version 1.2.2beta5 [March 26, 2002]
Added missing PNGAPI to several function definitions.
Check for invalid bit_depth or color_type in png_get_IHDR(), and
check for missing PLTE or IHDR in png_push_read_chunk() (Matthias Clasen).
Revised iTXt support to accept NULL for lang and lang_key.
Compute gamma for color components of background even when color_type is gray.
Changed "()" to "{}" in scripts/libpng.pc.in.
Revised makefiles to put png.h and pngconf.h only in $prefix/include/libpngNN
Revised makefiles to make symlink to libpng.so.NN in addition to libpngNN.so
Version 1.2.2beta6 [March 31, 2002]
Version 1.0.13beta1 [March 31, 2002]
Prevent png_zalloc() from trying to memset memory that it failed to acquire.
Add typecasts of PNG_MAX_UINT in pngset_cHRM_fixed() (Matt Holgate).
Ensure that the right function (user or default) is used to free the
src/Source/LibPNG/CHANGES view on Meta::CPAN
(John Bowler)
Version 1.4.0beta104 [November 22, 2009]
Removed png_longjmp_ptr from scripts/*.def and libpng.3
Rebuilt configure scripts with autoconf-2.65
Version 1.4.0beta105 [November 25, 2009]
Use fast integer PNG_DIVIDE_BY_255() or PNG_DIVIDE_BY_65535()
to accomplish alpha premultiplication when
PNG_READ_COMPOSITE_NODIV_SUPPORTED is defined.
Changed "/255" to "/255.0" in background calculations to make it clear
that the 255 is used as a double.
Version 1.4.0beta106 [November 27, 2009]
Removed premultiplied alpha feature.
Version 1.4.0beta107 [December 4, 2009]
Updated README
Added "#define PNG_NO_PEDANTIC_WARNINGS" in the libpng source files.
Removed "-DPNG_CONFIGURE_LIBPNG" from the makefiles and projects.
Revised scripts/makefile.netbsd, makefile.openbsd, and makefile.sco
src/Source/LibPNG/CHANGES view on Meta::CPAN
Version 1.5.0rc01 [December 27, 2010]
No changes.
Version 1.5.0rc02 [December 27, 2010]
Eliminated references to the scripts/*.def files in project/visualc71.
Version 1.5.0rc03 [December 28, 2010]
Eliminated scripts/*.def and revised Makefile.am accordingly
Version 1.5.0rc04 [December 29, 2010]
Fixed bug in background transformation handling in pngrtran.c (it was
looking for the flag in png_ptr->transformations instead of in
png_ptr->flags) (David Raymond).
Version 1.5.0rc05 [December 31, 2010]
Fixed typo in a comment in CMakeLists.txt (libpng14 => libpng15) (Cosmin)
Version 1.5.0rc06 [January 4, 2011]
Changed the new configure option "zprefix=string" to "zlib-prefix=string"
Version 1.5.0rc07 [January 4, 2011]
src/Source/LibPNG/CHANGES view on Meta::CPAN
issues a warning if there is a mistake (John Bowler).
Removed the no-longer-used PNG_DEPSTRUCT macro.
Updated the zlib version to 1.2.5 in the VStudio project.
Fixed 64-bit builds where png_uint_32 is smaller than png_size_t in
pngwutil.c (John Bowler).
Fixed bug with stripping the filler or alpha channel when writing, that
was introduced in libpng-1.5.2beta01 (bug report by Andrew Church).
Version 1.5.3beta04 [April 27, 2011]
Updated pngtest.png with the new zlib CMF optimization.
Cleaned up conditional compilation code and of background/gamma handling
Internal changes only except a new option to avoid compiling the
png_build_grayscale_palette API (which is not used at all internally.)
The main change is to move the transform tests (READ_TRANSFORMS,
WRITE_TRANSFORMS) up one level to the caller of the APIs. This avoids
calls to spurious functions if all transforms are disabled and slightly
simplifies those functions. Pngvalid modified to handle this.
A minor change is to stop the strip_16 and expand_16 interfaces from
disabling each other; this allows the future alpha premultiplication
code to use 16-bit intermediate values while still producing 8-bit output.
png_do_background and png_do_gamma have been simplified to take a single
pointer to the png_struct rather than pointers to every item required
from the png_struct. This makes no practical difference to the internal
code.
A serious bug in the pngvalid internal routine 'standard_display_init' has
been fixed - this failed to initialize the red channel and accidentally
initialized the alpha channel twice.
Changed png_struct jmp_buf member name from png_jmpbuf to tmp_jmpbuf to
avoid a possible clash with the png_jmpbuf macro on some platforms.
Version 1.5.3beta05 [May 6, 2011]
src/Source/LibPNG/CHANGES view on Meta::CPAN
Check for up->location !PNG_AFTER_IDAT when writing unknown chunks
before IDAT.
Version 1.5.3beta08 [May 16, 2011]
Improved "pngvalid --speed" to exclude more of pngvalid from the time.
Documented png_set_alpha_mode(), other changes in libpng.3/libpng-manual.txt
The cHRM chunk now sets the defaults for png_set_rgb_to_gray() (when negative
parameters are supplied by the caller), while in the absence of cHRM
sRGB/Rec 709 values are still used. This introduced a divide-by-zero
bug in png_handle_cHRM().
The bKGD chunk no longer overwrites the background value set by
png_set_background(), allowing the latter to be used before the file
header is read. It never performed any useful function to override
the default anyway.
Added memory overwrite and palette image checks to pngvalid.c
Previously palette image code was poorly checked. Since the transformation
code has a special palette path in most cases this was a severe weakness.
Minor cleanup and some extra checking in pngrutil.c and pngrtran.c. When
expanding an indexed image, always expand to RGBA if transparency is
present.
Version 1.5.3beta09 [May 17, 2011]
Reversed earlier 1.5.3 change of transformation order; move png_expand_16
back where it was. The change doesn't work because it requires 16-bit
gamma tables when the code only generates 8-bit ones. This fails
silently; the libpng code just doesn't do any gamma correction. Moving
the tests back leaves the old, inaccurate, 8-bit gamma calculations, but
these are clearly better than none!
Version 1.5.3beta10 [May 20, 2011]
png_set_background() and png_expand_16() did not work together correctly.
This problem is present in 1.5.2; if png_set_background is called with
need_expand false and the matching 16 bit color libpng erroneously just
treats it as an 8-bit color because of where png_do_expand_16 is in the
transform list. This simple fix reduces the supplied colour to 8-bits,
so it gets smashed, but this is better than the current behavior.
Added tests for expand16, more fixes for palette image tests to pngvalid.
Corrects the code for palette image tests and disables attempts to
validate palette colors.
Version 1.5.3rc01 [June 3, 2011]
No changes.
src/Source/LibPNG/CHANGES view on Meta::CPAN
to get the same (inaccurate) output as libpng-1.5.2 and earlier.
Moved definitions of PNG_HAVE_IHDR, PNG_AFTER_IDAT, and PNG_HAVE_PLTE
outside of an unknown-chunk block in png.h because they are also
needed for other uses.
Version 1.5.4beta02 [June 14, 2011]
Fixed and clarified LEGACY 16-to-8 scaling code.
Added png_set_chop_16() API, to match inaccurate results from previous
libpng versions.
Removed the ACCURATE and LEGACY options (they are no longer useable)
Use the old scaling method for background if png_set_chop_16() was
called.
Made png_set_chop_16() API removeable by disabling PNG_CHOP_16_TO_8_SUPPORTED
Version 1.5.4beta03 [June 15, 2011]
Fixed a problem in png_do_expand_palette() exposed by optimization in
1.5.3beta06
Also removed a spurious and confusing "trans" member ("trans") from png_info.
The palette expand optimization prevented expansion to an intermediate RGBA
form if tRNS was present but alpha was marked to be stripped; this exposed
a check for tRNS in png_do_expand_palette() which is inconsistent with the
src/Source/LibPNG/CHANGES view on Meta::CPAN
Version 1.6.0beta08 [February 1, 2012]
Fixed Image::colormap misalignment in pngstest.c
Check libtool/libtoolize version number (2.4.2) in configure.ac
Divide test-pngstest.sh into separate pngstest runs for basic and
transparent images.
Moved automake options to AM_INIT_AUTOMAKE in configure.ac
Added color-tests, silent-rules (Not yet implemented in Makefile.am) and
version checking to configure.ac
Improved pngstest speed by not doing redundant tests and add const to
the background parameter of png_image_finish_read. The --background
option is now done automagically only when required, so that commandline
option no longer exists.
Cleaned up pngpriv.h to consistently declare all functions and data.
Also eliminated PNG_CONST_DATA, which is apparently not needed but we
can't be sure until it is gone.
Added symbol prefixing that allows all the libpng external symbols
to be prefixed (suggested by Reuben Hawkins).
Updated "ftbb*.png" list in the owatcom and vstudio projects.
Fixed 'prefix' builds on clean systems. The generation of pngprefix.h
should not require itself.
src/Source/LibPNG/CHANGES view on Meta::CPAN
Add updated WARNING file to projects/vstudio from libpng 1.5/vstudio
Fixed build when using #define PNG_NO_READ_GAMMA in png_do_compose() in
pngrtran.c (Domani Hannes).
Version 1.6.0beta31 [November 1, 2012]
Undid the erroneous change to vstudio/pngvalid build in libpng-1.6.0beta30.
Made pngvalid so that it will build outside the libpng source tree.
Made builds -DPNG_NO_READ_GAMMA compile (the unit tests still fail).
Made PNG_NO_READ_GAMMA switch off interfaces that depend on READ_GAMMA.
Prior to 1.6.0 switching off READ_GAMMA did unpredictable things to the
interfaces that use it (specifically, png_do_background in 1.4 would
simply display composite for grayscale images but do composition
with the incorrect arithmetic for color ones). In 1.6 the semantic
of -DPNG_NO_READ_GAMMA is changed to simply disable any interface that
depends on it; this obliges people who set it to consider whether they
really want it off if they happen to use any of the interfaces in
question (typically most users who disable it won't).
Fixed GUIDs in projects/vstudio. Some were duplicated or missing,
resulting in VS2010 having to update the files.
Removed non-working ICC profile support code that was mostly added to
libpng-1.6.0beta29 and beta30. There was too much code for too little
src/Source/LibPNG/TODO view on Meta::CPAN
Complete sRGB transformation (presently it simply uses gamma=0.45455).
Make profile checking optional via a png_set_something() call.
Man pages for function calls.
Better documentation.
Better filter selection
(counting huffman bits/precompression? filter inertia? filter costs?).
Histogram creation.
Text conversion between different code pages (Latin-1 -> Mac and DOS).
Avoid building gamma tables whenever possible.
Use greater precision when changing to linear gamma for compositing against
background and doing rgb-to-gray transformation.
Investigate pre-incremented loop counters and other loop constructions.
Add interpolated method of handling interlacing.
Switch to the simpler zlib (zlib/libpng) license if legally possible.
Extend pngvalid.c to validate more of the libpng transformations.
*/
src/Source/LibPNG/example.c view on Meta::CPAN
*/
image.format = PNG_FORMAT_RGBA;
/* Now allocate enough memory to hold the image in this format; the
* PNG_IMAGE_SIZE macro uses the information about the image (width,
* height and format) stored in 'image'.
*/
buffer = malloc(PNG_IMAGE_SIZE(image));
/* If enough memory was available read the image in the desired format
* then write the result out to the new file. 'background' is not
* necessary when reading the image because the alpha channel is
* preserved; if it were to be removed, for example if we requested
* PNG_FORMAT_RGB, then either a solid background color would have to
* be supplied or the output buffer would have to be initialized to the
* actual background of the image.
*
* The fourth argument to png_image_finish_read is the 'row_stride' -
* this is the number of components allocated for the image in each
* row. It has to be at least as big as the value returned by
* PNG_IMAGE_ROW_STRIDE, but if you just allocate space for the
* default, minimum, size using PNG_IMAGE_SIZE as above you can pass
* zero.
*
* The final argument is a pointer to a buffer for the colormap;
* colormaps have exactly the same format as a row of image pixels (so
src/Source/LibPNG/example.c view on Meta::CPAN
* image.format). A colormap is only returned if
* PNG_FORMAT_FLAG_COLORMAP is also set in image.format, so in this
* case NULL is passed as the final argument. If you do want to force
* all images into an index/color-mapped format then you can use:
*
* PNG_IMAGE_COLORMAP_SIZE(image)
*
* to find the maximum size of the colormap in bytes.
*/
if (buffer != NULL &&
png_image_finish_read(&image, NULL/*background*/, buffer,
0/*row_stride*/, NULL/*colormap*/) != 0)
{
/* Now write the image out to the second argument. In the write
* call 'convert_to_8bit' allows 16-bit data to be squashed down to
* 8 bits; this isn't necessary here because the original read was
* to the 8-bit format.
*/
if (png_image_write_to_file(&image, argv[2], 0/*convert_to_8bit*/,
buffer, 0/*row_stride*/, NULL/*colormap*/) != 0)
{
src/Source/LibPNG/example.c view on Meta::CPAN
#endif no_streams /* Use only one I/O method! */
/* If we have already read some of the signature */
png_set_sig_bytes(png_ptr, sig_read);
#ifdef hilevel
/*
* If you have enough memory to read in the entire image at once,
* and you need to specify only transforms that can be controlled
* with one of the PNG_TRANSFORM_* bits (this presently excludes
* quantizing, filling, setting background, and doing gamma
* adjustment), then you can read the entire image (including
* pixels) into the info structure with this call:
*/
png_read_png(png_ptr, info_ptr, png_transforms, NULL);
#else
/* OK, you're doing it the hard way, with the lower-level functions */
/* The call to png_read_info() gives us all of the information from the
* PNG file before the first IDAT (image data chunk). REQUIRED
src/Source/LibPNG/example.c view on Meta::CPAN
* Use accurate scaling if it's available, otherwise just chop off the
* low byte.
*/
#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
png_set_scale_16(png_ptr);
#else
png_set_strip_16(png_ptr);
#endif
/* Strip alpha bytes from the input data without combining with the
* background (not recommended).
*/
png_set_strip_alpha(png_ptr);
/* Extract multiple pixels with bit depths of 1, 2, and 4 from a single
* byte into separate bytes (useful for paletted and grayscale images).
*/
png_set_packing(png_ptr);
/* Change the order of packed pixels to least significant bit first
* (not useful if you are using png_set_packing). */
src/Source/LibPNG/example.c view on Meta::CPAN
/* Expand grayscale images to the full 8 bits from 1, 2, or 4 bits/pixel */
if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
png_set_expand_gray_1_2_4_to_8(png_ptr);
/* Expand paletted or RGB images with transparency to full alpha channels
* so the data will be available as RGBA quartets.
*/
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS) != 0)
png_set_tRNS_to_alpha(png_ptr);
/* Set the background color to draw transparent and alpha images over.
* It is possible to set the red, green, and blue components directly
* for paletted images instead of supplying a palette index. Note that
* even if the PNG file supplies a background, you are not required to
* use it - you should use the (solid) application background if it has one.
*/
png_color_16 my_background, *image_background;
if (png_get_bKGD(png_ptr, info_ptr, &image_background) != 0)
png_set_background(png_ptr, image_background,
PNG_BACKGROUND_GAMMA_FILE, 1, 1.0);
else
png_set_background(png_ptr, &my_background,
PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0);
/* Some suggestions as to how to get a screen gamma value
*
* Note that screen gamma is the display_exponent, which includes
* the CRT_exponent and any correction for viewing conditions
*/
if (/* We have a user-defined screen gamma value */)
{
screen_gamma = user-defined screen_gamma;
src/Source/LibPNG/example.c view on Meta::CPAN
/* Turn on interlace handling. REQUIRED if you are not using
* png_read_image(). To see how to handle interlacing passes,
* see the png_read_row() method below:
*/
number_passes = png_set_interlace_handling(png_ptr);
#else
number_passes = 1;
#endif /* READ_INTERLACING */
/* Optional call to gamma correct and add the background to the palette
* and update info structure. REQUIRED if you are expecting libpng to
* update the palette for you (ie you selected such a transform above).
*/
png_read_update_info(png_ptr, info_ptr);
/* Allocate the memory to hold the image using the fields of info_ptr. */
/* The easiest way to read the image: */
png_bytep row_pointers[height];
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
Both these values are reserved (not simple gamma values) in order to allow
more precise correction internally in the future.
NOTE: the values can be passed to either the fixed or floating
point APIs, but the floating point API will also accept floating point
values.
The second thing you may need to tell libpng about is how your system handles
alpha channel information. Some, but not all, PNG files contain an alpha
channel. To display these files correctly you need to compose the data onto a
suitable background, as described in the PNG specification.
Libpng only supports composing onto a single color (using png_set_background;
see below). Otherwise you must do the composition yourself and, in this case,
you may need to call png_set_alpha_mode:
#if PNG_LIBPNG_VER >= 10504
png_set_alpha_mode(png_ptr, mode, screen_gamma);
#else
png_set_gamma(png_ptr, screen_gamma, 1.0/screen_gamma);
#endif
The screen_gamma value is the same as the argument to png_set_gamma; however,
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
it might look better.
PNG_ALPHA_BROKEN: This is PNG_ALPHA_STANDARD; however, all component
values, including the alpha channel are gamma encoded. This is
broken because, in practice, no implementation that uses this choice
correctly undoes the encoding before handling alpha composition. Use this
choice only if other serious errors in the software or hardware you use
mandate it. In most cases of broken software or hardware the bug in the
final display manifests as a subtle halo around composited parts of the
image. You may not even perceive this as a halo; the composited part of
the image may simply appear separate from the background, as though it had
been cut out of paper and pasted on afterward.
If you don't have to deal with bugs in software or hardware, or if you can fix
them, there are three recommended ways of using png_set_alpha_mode():
png_set_alpha_mode(png_ptr, PNG_ALPHA_PNG,
screen_gamma);
You can do color correction on the result (libpng does not currently
support color correction internally). When you handle the alpha channel
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
This is a somewhat more realistic Jim Blinn inspired approach. PNG files
are assumed to have the sRGB encoding if not marked with a gamma value and
the output is always 16 bits per component. This permits accurate scaling
and processing of the data. If you know that your input PNG files were
generated locally you might need to replace PNG_DEFAULT_sRGB with the
correct value for your system.
png_set_alpha_mode(pp, PNG_ALPHA_OPTIMIZED, PNG_DEFAULT_sRGB);
If you just need to composite the PNG image onto an existing background
and if you control the code that does this you can use the optimization
setting. In this case you just copy completely opaque pixels to the
output. For pixels that are not completely transparent (you just skip
those) you do the composition math using png_composite or png_composite_16
below then encode the resultant 8-bit or 16-bit values to match the output
encoding.
Other cases
If neither the PNG nor the standard linear encoding work for you because
of the software or hardware you use then you have a big problem. The PNG
case will probably result in halos around the image. The linear encoding
will probably result in a washed out, too bright, image (it's actually too
contrasty.) Try the ALPHA_OPTIMIZED mode above - this will probably
substantially reduce the halos. Alternatively try:
png_set_alpha_mode(pp, PNG_ALPHA_BROKEN, PNG_DEFAULT_sRGB);
This option will also reduce the halos, but there will be slight dark
halos round the opaque parts of the image where the background is light.
In the OPTIMIZED mode the halos will be light halos where the background
is dark. Take your pick - the halos are unavoidable unless you can get
your hardware/software fixed! (The OPTIMIZED approach is slightly
faster.)
When the default gamma of PNG files doesn't match the output gamma.
If you have PNG files with no gamma information png_set_alpha_mode allows
you to provide a default gamma, but it also sets the ouput gamma to the
matching value. If you know your PNG files have a gamma that doesn't
match the output you can take advantage of the fact that
png_set_alpha_mode always sets the output gamma but only sets the PNG
default if it is not already set:
png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
The first call sets both the default and the output gamma values, the
second call overrides the output gamma without changing the default. This
is easier than achieving the same effect with png_set_gamma. You must use
PNG_ALPHA_PNG for the first call - internal checking in png_set_alpha will
fire if more than one call to png_set_alpha_mode and png_set_background is
made in the same read operation, however multiple calls with PNG_ALPHA_PNG
are ignored.
If you don't need, or can't handle, the alpha channel you can call
png_set_background() to remove it by compositing against a fixed color. Don't
call png_set_strip_alpha() to do this - it will leave spurious pixel values in
transparent parts of this image.
png_set_background(png_ptr, &background_color,
PNG_BACKGROUND_GAMMA_SCREEN, 0, 1);
The background_color is an RGB or grayscale value according to the data format
libpng will produce for you. Because you don't yet know the format of the PNG
file, if you call png_set_background at this point you must arrange for the
format produced by libpng to always have 8-bit or 16-bit components and then
store the color as an 8-bit or 16-bit color as appropriate. The color contains
separate gray and RGB component values, so you can let libpng produce gray or
RGB output according to the input format, but low bit depth grayscale images
must always be converted to at least 8-bit format. (Even though low bit depth
grayscale images can't have an alpha channel they can have a transparent
color!)
You set the transforms you need later, either as flags to the high level
interface or libpng API calls for the low level interface. For reference the
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
instead.
16-bit values:
PNG_TRANSFORM_EXPAND_16
png_set_expand_16(png_ptr);
In either case palette image data will be expanded to RGB. If you just want
color data you can add PNG_TRANSFORM_GRAY_TO_RGB or png_set_gray_to_rgb(png_ptr)
to the list.
Calling png_set_background before the PNG file header is read will not work
prior to libpng-1.5.4. Because the failure may result in unexpected warnings or
errors it is therefore much safer to call png_set_background after the head has
been read. Unfortunately this means that prior to libpng-1.5.4 it cannot be
used with the high level interface.
The high-level read interface
At this point there are two ways to proceed; through the high-level
read interface, or through a sequence of low-level read operations.
You can use the high-level interface if (a) you are willing to read
the entire image into memory, and (b) the input transformations
you want to do are limited to the following set:
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
to BGRA
PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA
to AG
PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity
to transparency
PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples
PNG_TRANSFORM_GRAY_TO_RGB Expand grayscale samples
to RGB (or GA to RGBA)
PNG_TRANSFORM_EXPAND_16 Expand samples to 16 bits
(This excludes setting a background color, doing gamma transformation,
quantizing, and setting filler.) If this is the case, simply do this:
png_read_png(png_ptr, info_ptr, png_transforms, NULL)
where png_transforms is an integer containing the bitwise OR of some
set of transformation flags. This call is equivalent to png_read_info(),
followed the set of transformations indicated by the transform mask,
then png_read_image(), and finally png_read_end().
(The final parameter of this call is not yet used. Someday it might point
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
png_read_info(png_ptr, info_ptr);
This will process all chunks up to but not including the image data.
This also copies some of the data from the PNG file into the decode structure
for use in later transformations. Important information copied in is:
1) The PNG file gamma from the gAMA chunk. This overwrites the default value
provided by an earlier call to png_set_gamma or png_set_alpha_mode.
2) Prior to libpng-1.5.4 the background color from a bKGd chunk. This
damages the information provided by an earlier call to png_set_background
resulting in unexpected behavior. Libpng-1.5.4 no longer does this.
3) The number of significant bits in each component value. Libpng uses this to
optimize gamma handling by reducing the internal lookup table sizes.
4) The transparent color information from a tRNS chunk. This can be modified by
a later call to png_set_tRNS.
Querying the info structure
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
These are also important, but their validity depends on whether the chunk
has been read. The png_get_valid(png_ptr, info_ptr, PNG_INFO_<chunk>) and
png_get_<chunk>(png_ptr, info_ptr, ...) functions return non-zero if the
data has been read, or zero if it is missing. The parameters to the
png_get_<chunk> are set directly if they are simple data types, or a
pointer into the info_ptr is returned for any complex types.
The colorspace data from gAMA, cHRM, sRGB, iCCP, and sBIT chunks
is simply returned to give the application information about how the
image was encoded. Libpng itself only does transformations using the file
gamma when combining semitransparent pixels with the background color, and,
since libpng-1.6.0, when converting between 8-bit sRGB and 16-bit linear pixels
within the simplified API. Libpng also uses the file gamma when converting
RGB to gray, beginning with libpng-1.0.5, if the application calls
png_set_rgb_to_gray()).
png_get_PLTE(png_ptr, info_ptr, &palette,
&num_palette);
palette - the palette for the file
(array of png_color)
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
(PNG_INFO_hIST)
hist - histogram of palette (array of
png_uint_16)
png_get_tIME(png_ptr, info_ptr, &mod_time);
mod_time - time image was last modified
(PNG_VALID_tIME)
png_get_bKGD(png_ptr, info_ptr, &background);
background - background color (of type
png_color_16p) (PNG_VALID_bKGD)
valid 16-bit red, green and blue
values, regardless of color_type
num_comments = png_get_text(png_ptr, info_ptr,
&text_ptr, &num_text);
num_comments - number of comments
text_ptr - array of png_text holding image
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
Transformations you request are ignored if they don't have any meaning for a
particular input data format. However some transformations can have an effect
as a result of a previous transformation. If you specify a contradictory set of
transformations, for example both adding and removing the alpha channel, you
cannot predict the final result.
The color used for the transparency values should be supplied in the same
format/depth as the current image data. It is stored in the same format/depth
as the image data in a tRNS chunk, so this is what libpng expects for this data.
The color used for the background value depends on the need_expand argument as
described below.
Data will be decoded into the supplied row buffers packed into bytes
unless the library has been told to transform it into another format.
For example, 4 bit/pixel paletted or grayscale data will be returned
2 pixels/byte with the leftmost pixel in the high-order bits of the
byte, unless png_set_packing() is called. 8-bit RGB data will be stored
in RGB RGB RGB format unless png_set_filler() or png_set_add_alpha()
is called to insert filler bytes, either before or after each RGB triplet.
16-bit RGB data will be returned RRGGBB RRGGBB, with the most significant
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
If you need to process the alpha channel on the image separately from the image
data (for example if you convert it to a bitmap mask) it is possible to have
libpng strip the channel leaving just RGB or gray data:
if (color_type & PNG_COLOR_MASK_ALPHA)
png_set_strip_alpha(png_ptr);
If you strip the alpha channel you need to find some other way of dealing with
the information. If, instead, you want to convert the image to an opaque
version with no alpha channel use png_set_background; see below.
As of libpng version 1.5.2, almost all useful expansions are supported, the
major ommissions are conversion of grayscale to indexed images (which can be
done trivially in the application) and conversion of indexed to grayscale (which
can be done by a trivial manipulation of the palette.)
In the following table, the 01 means grayscale with depth<8, 31 means
indexed with depth<8, other numerals represent the color type, "T" means
the tRNS chunk is present, A means an alpha channel is present, and O
means tRNS or alpha is present but all pixels in the image are opaque.
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
format).
"C" means the transformation is obtained by png_set_gray_to_rgb().
"G" means the transformation is obtained by png_set_rgb_to_gray().
"P" means the transformation is obtained by
png_set_expand_palette_to_rgb().
"p" means the transformation is obtained by png_set_packing().
"Q" means the transformation is obtained by png_set_quantize().
"T" means the transformation is obtained by
png_set_tRNS_to_alpha().
"B" means the transformation is obtained by
png_set_background(), or png_strip_alpha().
When an entry has multiple transforms listed all are required to cause the
right overall transformation. When two transforms are separated by a comma
either will do the job. When transforms are enclosed in [] the transform should
do the job but this is currently unimplemented - a different format will result
if the suggested transformations are used.
In PNG files, the alpha channel in an image
is the level of opacity. If you need the alpha channel in an image to
be the level of transparency instead of opacity, you can invert the
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
Libpng uses an integer approximation:
Y = (6968 * R + 23434 * G + 2366 * B)/32768
The calculation is done in a linear colorspace, if the image gamma
can be determined.
The png_set_background() function has been described already; it tells libpng to
composite images with alpha or simple transparency against the supplied
background color. For compatibility with versions of libpng earlier than
libpng-1.5.4 it is recommended that you call the function after reading the file
header, even if you don't want to use the color in a bKGD chunk, if one exists.
If the PNG file contains a bKGD chunk (PNG_INFO_bKGD valid),
you may use this color, or supply another color more suitable for
the current display (e.g., the background color from a web page). You
need to tell libpng how the color is represented, both the format of the
component values in the color (the number of bits) and the gamma encoding of the
color. The function takes two arguments, background_gamma_mode and need_expand
to convey this information; however, only two combinations are likely to be
useful:
png_color_16 my_background;
png_color_16p image_background;
if (png_get_bKGD(png_ptr, info_ptr, &image_background))
png_set_background(png_ptr, image_background,
PNG_BACKGROUND_GAMMA_FILE, 1/*needs to be expanded*/, 1);
else
png_set_background(png_ptr, &my_background,
PNG_BACKGROUND_GAMMA_SCREEN, 0/*do not expand*/, 1);
The second call was described above - my_background is in the format of the
final, display, output produced by libpng. Because you now know the format of
the PNG it is possible to avoid the need to choose either 8-bit or 16-bit
output and to retain palette images (the palette colors will be modified
appropriately and the tRNS chunk removed.) However, if you are doing this,
take great care not to ask for transformations without checking first that
they apply!
In the first call the background color has the original bit depth and color type
of the PNG file. So, for palette images the color is supplied as a palette
index and for low bit greyscale images the color is a reduced bit value in
image_background->gray.
If you didn't call png_set_gamma() before reading the file header, for example
if you need your code to remain compatible with older versions of libpng prior
to libpng-1.5.4, this is the place to call it.
Do not call it if you called png_set_alpha_mode(); doing so will damage the
settings put in place by png_set_alpha_mode(). (If png_set_alpha_mode() is
supported then you can certainly do png_set_gamma() before reading the PNG
header.)
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
After setting the transformations, libpng can update your png_info
structure to reflect any transformations you've requested with this
call.
png_read_update_info(png_ptr, info_ptr);
This is most useful to update the info structure's rowbytes
field so you can use it to allocate your image memory. This function
will also update your palette with the correct screen_gamma and
background if these have been given with the calls above. You may
only call png_read_update_info() once with a particular info_ptr.
After you call png_read_update_info(), you can allocate any
memory you need to hold the image. The row data is simply
raw byte data for all forms of images. As the actual allocation
varies among applications, no example will be given. If you
are allocating one large chunk, you will need to build an
array of pointers to each row, as it will be needed for some
of the functions below.
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
png_set_hIST(png_ptr, info_ptr, hist);
hist - histogram of palette (array of
png_uint_16) (PNG_INFO_hIST)
png_set_tIME(png_ptr, info_ptr, mod_time);
mod_time - time image was last modified
(PNG_VALID_tIME)
png_set_bKGD(png_ptr, info_ptr, background);
background - background color (of type
png_color_16p) (PNG_VALID_bKGD)
png_set_text(png_ptr, info_ptr, text_ptr, num_text);
text_ptr - array of png_text holding image
comments
text_ptr[i].compression - type of compression used
on "text" PNG_TEXT_COMPRESSION_NONE
PNG_TEXT_COMPRESSION_zTXt
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
FILE* file)
The PNG header is read from the stdio FILE object.
int png_image_begin_read_from_memory(png_imagep image,
png_const_voidp memory, png_size_t size)
The PNG header is read from the given memory buffer.
int png_image_finish_read(png_imagep image,
png_colorp background, void *buffer,
png_int_32 row_stride, void *colormap));
Finish reading the image into the supplied buffer and
clean up the png_image structure.
row_stride is the step, in png_byte or png_uint_16 units
as appropriate, between adjacent rows. A positive stride
indicates that the top-most row is first in the buffer -
the normal top-down arrangement. A negative stride
indicates that the bottom-most row is first in the buffer.
background need only be supplied if an alpha channel must
be removed from a png_byte format and the removal is to be
done by compositing on a solid color; otherwise it may be
NULL and any composition will be done directly onto the
buffer. The value is an sRGB color to use for the
background, for grayscale output the green channel is used.
For linear output removing the alpha channel is always done
by compositing on black.
void png_image_free(png_imagep image)
Free any data allocated by libpng in image->opaque,
setting the pointer to NULL. May be called at any time
after the structure is initialized.
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
libpng 1.5.0 includes a complete fixed point API. By default this is
present along with the corresponding floating point API. In general the
fixed point API is faster and smaller than the floating point one because
the PNG file format used fixed point, not floating point. This applies
even if the library uses floating point in internal calculations. A new
macro, PNG_FLOATING_ARITHMETIC_SUPPORTED, reveals whether the library
uses floating point arithmetic (the default) or fixed point arithmetic
internally for performance critical calculations such as gamma correction.
In some cases, the gamma calculations may produce slightly different
results. This has changed the results in png_rgb_to_gray and in alpha
composition (png_set_background for example). This applies even if the
original image was already linear (gamma == 1.0) and, therefore, it is
not necessary to linearize the image. This is because libpng has *not*
been changed to optimize that case correctly, yet.
Fixed point support for the sCAL chunk comes with an important caveat;
the sCAL specification uses a decimal encoding of floating point values
and the accuracy of PNG fixed point values is insufficient for
representation of these values. Consequently a "string" API
(png_get_sCAL_s and png_set_sCAL_s) is the only reliable way of reading
arbitrary sCAL chunks in the absence of either the floating point API or
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
are allowed by the PNG specification, so these warnings are no longer issued.
The library now issues an error if the application attempts to set a
transform after it calls png_read_update_info() or if it attempts to call
both png_read_update_info() and png_start_read_image() or to call either
of them more than once.
The default condition for benign_errors is now to treat benign errors as
warnings while reading and as errors while writing.
The library now issues a warning if both background processing and RGB to
gray are used when gamma correction happens. As with previous versions of
the library the results are numerically very incorrect in this case.
There are some minor arithmetic changes in some transforms such as
png_set_background(), that might be detected by certain regression tests.
Unknown chunk handling has been improved internally, without any API change.
This adds more correct option control of the unknown handling, corrects
a pre-existing bug where the per-chunk 'keep' setting is ignored, and makes
it possible to skip IDAT chunks in the sequential reader.
The machine-generated configure files are no longer included in branches
libpng16 and later of the GIT repository. They continue to be included
in the tarball releases, however.
src/Source/LibPNG/libpng.3 view on Meta::CPAN
\fBvoid png_free (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fIptr\fP\fB);\fP
\fBvoid png_free_chunk_list (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_free_default (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fIptr\fP\fB);\fP
\fBvoid png_free_data (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fInum\fP\fB);\fP
\fBpng_byte png_get_bit_depth (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_bKGD (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_16p \fI*background\fP\fB);\fP
\fBpng_byte png_get_channels (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_cHRM (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, double \fP\fI*white_x\fP\fB, double \fP\fI*white_y\fP\fB, double \fP\fI*red_x\fP\fB, double \fP\fI*red_y\fP\fB, double \fP\fI*green_x\fP\fB, dou...
\fBpng_uint_32 png_get_cHRM_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*white_x\fP\fB, png_uint_32 \fP\fI*white_y\fP\fB, png_uint_32 \fP\fI*red_x\fP\fB, png_uint_32 \fP\fI*red_y\fP\fB, png_ui...
\fBpng_uint_32 png_get_cHRM_XYZ (png_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, double \fP\fI*red_X\fP\fB, double \fP\fI*red_Y\fP\fB, double \fP\fI*red_Z\fP\fB, double \fP\fI*green_X\fP\fB, double \fP\fI*green_Y\fP\fB, double ...
\fBpng_uint_32 png_get_cHRM_XYZ_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_fixed_point \fP\fI*int_red_X\fP\fB, png_fixed_point \fP\fI*int_red_Y\fP\fB, png_fixed_point \fP\fI*int_red_Z\fP\fB, png_fixed_point \fP\...
src/Source/LibPNG/libpng.3 view on Meta::CPAN
\fBpng_uint_32 png_get_y_pixels_per_meter (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBint png_handle_as_unknown (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIchunk_name\fP\fB);\fP
\fBint png_image_begin_read_from_file (png_imagep \fP\fIimage\fP\fB, const char \fI*file_name\fP\fB);\fP
\fBint png_image_begin_read_from_stdio (png_imagep \fP\fIimage\fP\fB, FILE* \fIfile\fP\fB);\fP
\fBint, png_image_begin_read_from_memory (png_imagep \fP\fIimage\fP\fB, png_const_voidp \fP\fImemory\fP\fB, png_size_t \fIsize\fP\fB);\fP
\fBint png_image_finish_read (png_imagep \fP\fIimage\fP\fB, png_colorp \fP\fIbackground\fP\fB, void \fP\fI*buffer\fP\fB, png_int_32 \fP\fIrow_stride\fP\fB, void \fI*colormap\fP\fB);\fP
\fBvoid png_image_free (png_imagep \fIimage\fP\fB);\fP
\fBint png_image_write_to_file (png_imagep \fP\fIimage\fP\fB, const char \fP\fI*file\fP\fB, int \fP\fIconvert_to_8bit\fP\fB, const void \fP\fI*buffer\fP\fB, png_int_32 \fP\fIrow_stride\fP\fB, void \fI*colormap\fP\fB);\fP
\fBint png_image_write_to_stdio (png_imagep \fP\fIimage\fP\fB, FILE \fP\fI*file\fP\fB, int \fP\fIconvert_to_8_bit\fP\fB, const void \fP\fI*buffer\fP\fB, png_int_32 \fP\fIrow_stride\fP\fB, void \fI*colormap)\fP\fB);\fP
\fBvoid png_info_init_3 (png_infopp \fP\fIinfo_ptr\fP\fB, png_size_t \fIpng_info_struct_size\fP\fB);\fP
\fBvoid png_init_io (png_structp \fP\fIpng_ptr\fP\fB, FILE \fI*fp\fP\fB);\fP
src/Source/LibPNG/libpng.3 view on Meta::CPAN
\fBvoid png_save_uint_16 (png_bytep \fP\fIbuf\fP\fB, unsigned int \fIi\fP\fB);\fP
\fBvoid png_save_uint_32 (png_bytep \fP\fIbuf\fP\fB, png_uint_32 \fIi\fP\fB);\fP
\fBvoid png_set_add_alpha (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIfiller\fP\fB, int \fIflags\fP\fB);\fP
\fBvoid png_set_alpha_mode (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fImode\fP\fB, double \fIoutput_gamma\fP\fB);\fP
\fBvoid png_set_alpha_mode_fixed (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fImode\fP\fB, png_fixed_point \fIoutput_gamma\fP\fB);\fP
\fBvoid png_set_background (png_structp \fP\fIpng_ptr\fP\fB, png_color_16p \fP\fIbackground_color\fP\fB, int \fP\fIbackground_gamma_code\fP\fB, int \fP\fIneed_expand\fP\fB, double \fIbackground_gamma\fP\fB);\fP
\fBvoid png_set_background_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_color_16p \fP\fIbackground_color\fP\fB, int \fP\fIbackground_gamma_code\fP\fB, int \fP\fIneed_expand\fP\fB, png_uint_32 \fIbackground_gamma\fP\fB);\fP
\fBvoid png_set_benign_errors (png_structp \fP\fIpng_ptr\fP\fB, int \fIallowed\fP\fB);\fP
\fBvoid png_set_bgr (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_set_bKGD (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_16p \fIbackground\fP\fB);\fP
\fBvoid png_set_check_for_invalid_index(png_structrp \fP\fIpng_ptr\fP\fB, int \fIallowed\fP\fB);\fP
\fBvoid png_set_cHRM (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fP\fIwhite_x\fP\fB, double \fP\fIwhite_y\fP\fB, double \fP\fIred_x\fP\fB, double \fP\fIred_y\fP\fB, double \fP\fIgreen_x\fP\fB, double \fP\fIgreen_y\fP\fB,...
\fBvoid png_set_cHRM_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIwhite_x\fP\fB, png_uint_32 \fP\fIwhite_y\fP\fB, png_uint_32 \fP\fIred_x\fP\fB, png_uint_32 \fP\fIred_y\fP\fB, png_uint_32 \fP\fIgreen_x\fP\...
\fBvoid png_set_cHRM_XYZ (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fP\fIred_X\fP\fB, double \fP\fIred_Y\fP\fB, double \fP\fIred_Z\fP\fB, double \fP\fIgreen_X\fP\fB, double \fP\fIgreen_Y\fP\fB, double \fP\fIgreen_Z\fP\f...
\fBvoid png_set_cHRM_XYZ_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_fixed_point \fP\fIint_red_X\fP\fB, png_fixed_point \fP\fIint_red_Y\fP\fB, png_fixed_point \fP\fIint_red_Z\fP\fB, png_fixed_point \fP\fIint_green_X\fP...
src/Source/LibPNG/libpng.3 view on Meta::CPAN
Both these values are reserved (not simple gamma values) in order to allow
more precise correction internally in the future.
NOTE: the values can be passed to either the fixed or floating
point APIs, but the floating point API will also accept floating point
values.
The second thing you may need to tell libpng about is how your system handles
alpha channel information. Some, but not all, PNG files contain an alpha
channel. To display these files correctly you need to compose the data onto a
suitable background, as described in the PNG specification.
Libpng only supports composing onto a single color (using png_set_background;
see below). Otherwise you must do the composition yourself and, in this case,
you may need to call png_set_alpha_mode:
#if PNG_LIBPNG_VER >= 10504
png_set_alpha_mode(png_ptr, mode, screen_gamma);
#else
png_set_gamma(png_ptr, screen_gamma, 1.0/screen_gamma);
#endif
The screen_gamma value is the same as the argument to png_set_gamma; however,
src/Source/LibPNG/libpng.3 view on Meta::CPAN
it might look better.
PNG_ALPHA_BROKEN: This is PNG_ALPHA_STANDARD; however, all component
values, including the alpha channel are gamma encoded. This is
broken because, in practice, no implementation that uses this choice
correctly undoes the encoding before handling alpha composition. Use this
choice only if other serious errors in the software or hardware you use
mandate it. In most cases of broken software or hardware the bug in the
final display manifests as a subtle halo around composited parts of the
image. You may not even perceive this as a halo; the composited part of
the image may simply appear separate from the background, as though it had
been cut out of paper and pasted on afterward.
If you don't have to deal with bugs in software or hardware, or if you can fix
them, there are three recommended ways of using png_set_alpha_mode():
png_set_alpha_mode(png_ptr, PNG_ALPHA_PNG,
screen_gamma);
You can do color correction on the result (libpng does not currently
support color correction internally). When you handle the alpha channel
src/Source/LibPNG/libpng.3 view on Meta::CPAN
This is a somewhat more realistic Jim Blinn inspired approach. PNG files
are assumed to have the sRGB encoding if not marked with a gamma value and
the output is always 16 bits per component. This permits accurate scaling
and processing of the data. If you know that your input PNG files were
generated locally you might need to replace PNG_DEFAULT_sRGB with the
correct value for your system.
png_set_alpha_mode(pp, PNG_ALPHA_OPTIMIZED, PNG_DEFAULT_sRGB);
If you just need to composite the PNG image onto an existing background
and if you control the code that does this you can use the optimization
setting. In this case you just copy completely opaque pixels to the
output. For pixels that are not completely transparent (you just skip
those) you do the composition math using png_composite or png_composite_16
below then encode the resultant 8-bit or 16-bit values to match the output
encoding.
Other cases
If neither the PNG nor the standard linear encoding work for you because
of the software or hardware you use then you have a big problem. The PNG
case will probably result in halos around the image. The linear encoding
will probably result in a washed out, too bright, image (it's actually too
contrasty.) Try the ALPHA_OPTIMIZED mode above - this will probably
substantially reduce the halos. Alternatively try:
png_set_alpha_mode(pp, PNG_ALPHA_BROKEN, PNG_DEFAULT_sRGB);
This option will also reduce the halos, but there will be slight dark
halos round the opaque parts of the image where the background is light.
In the OPTIMIZED mode the halos will be light halos where the background
is dark. Take your pick - the halos are unavoidable unless you can get
your hardware/software fixed! (The OPTIMIZED approach is slightly
faster.)
When the default gamma of PNG files doesn't match the output gamma.
If you have PNG files with no gamma information png_set_alpha_mode allows
you to provide a default gamma, but it also sets the ouput gamma to the
matching value. If you know your PNG files have a gamma that doesn't
match the output you can take advantage of the fact that
png_set_alpha_mode always sets the output gamma but only sets the PNG
default if it is not already set:
png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
The first call sets both the default and the output gamma values, the
second call overrides the output gamma without changing the default. This
is easier than achieving the same effect with png_set_gamma. You must use
PNG_ALPHA_PNG for the first call - internal checking in png_set_alpha will
fire if more than one call to png_set_alpha_mode and png_set_background is
made in the same read operation, however multiple calls with PNG_ALPHA_PNG
are ignored.
If you don't need, or can't handle, the alpha channel you can call
png_set_background() to remove it by compositing against a fixed color. Don't
call png_set_strip_alpha() to do this - it will leave spurious pixel values in
transparent parts of this image.
png_set_background(png_ptr, &background_color,
PNG_BACKGROUND_GAMMA_SCREEN, 0, 1);
The background_color is an RGB or grayscale value according to the data format
libpng will produce for you. Because you don't yet know the format of the PNG
file, if you call png_set_background at this point you must arrange for the
format produced by libpng to always have 8-bit or 16-bit components and then
store the color as an 8-bit or 16-bit color as appropriate. The color contains
separate gray and RGB component values, so you can let libpng produce gray or
RGB output according to the input format, but low bit depth grayscale images
must always be converted to at least 8-bit format. (Even though low bit depth
grayscale images can't have an alpha channel they can have a transparent
color!)
You set the transforms you need later, either as flags to the high level
interface or libpng API calls for the low level interface. For reference the
src/Source/LibPNG/libpng.3 view on Meta::CPAN
instead.
16-bit values:
PNG_TRANSFORM_EXPAND_16
png_set_expand_16(png_ptr);
In either case palette image data will be expanded to RGB. If you just want
color data you can add PNG_TRANSFORM_GRAY_TO_RGB or png_set_gray_to_rgb(png_ptr)
to the list.
Calling png_set_background before the PNG file header is read will not work
prior to libpng-1.5.4. Because the failure may result in unexpected warnings or
errors it is therefore much safer to call png_set_background after the head has
been read. Unfortunately this means that prior to libpng-1.5.4 it cannot be
used with the high level interface.
.SS The high-level read interface
At this point there are two ways to proceed; through the high-level
read interface, or through a sequence of low-level read operations.
You can use the high-level interface if (a) you are willing to read
the entire image into memory, and (b) the input transformations
you want to do are limited to the following set:
src/Source/LibPNG/libpng.3 view on Meta::CPAN
to BGRA
PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA
to AG
PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity
to transparency
PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples
PNG_TRANSFORM_GRAY_TO_RGB Expand grayscale samples
to RGB (or GA to RGBA)
PNG_TRANSFORM_EXPAND_16 Expand samples to 16 bits
(This excludes setting a background color, doing gamma transformation,
quantizing, and setting filler.) If this is the case, simply do this:
png_read_png(png_ptr, info_ptr, png_transforms, NULL)
where png_transforms is an integer containing the bitwise OR of some
set of transformation flags. This call is equivalent to png_read_info(),
followed the set of transformations indicated by the transform mask,
then png_read_image(), and finally png_read_end().
(The final parameter of this call is not yet used. Someday it might point
src/Source/LibPNG/libpng.3 view on Meta::CPAN
png_read_info(png_ptr, info_ptr);
This will process all chunks up to but not including the image data.
This also copies some of the data from the PNG file into the decode structure
for use in later transformations. Important information copied in is:
1) The PNG file gamma from the gAMA chunk. This overwrites the default value
provided by an earlier call to png_set_gamma or png_set_alpha_mode.
2) Prior to libpng-1.5.4 the background color from a bKGd chunk. This
damages the information provided by an earlier call to png_set_background
resulting in unexpected behavior. Libpng-1.5.4 no longer does this.
3) The number of significant bits in each component value. Libpng uses this to
optimize gamma handling by reducing the internal lookup table sizes.
4) The transparent color information from a tRNS chunk. This can be modified by
a later call to png_set_tRNS.
.SS Querying the info structure
src/Source/LibPNG/libpng.3 view on Meta::CPAN
These are also important, but their validity depends on whether the chunk
has been read. The png_get_valid(png_ptr, info_ptr, PNG_INFO_<chunk>) and
png_get_<chunk>(png_ptr, info_ptr, ...) functions return non-zero if the
data has been read, or zero if it is missing. The parameters to the
png_get_<chunk> are set directly if they are simple data types, or a
pointer into the info_ptr is returned for any complex types.
The colorspace data from gAMA, cHRM, sRGB, iCCP, and sBIT chunks
is simply returned to give the application information about how the
image was encoded. Libpng itself only does transformations using the file
gamma when combining semitransparent pixels with the background color, and,
since libpng-1.6.0, when converting between 8-bit sRGB and 16-bit linear pixels
within the simplified API. Libpng also uses the file gamma when converting
RGB to gray, beginning with libpng-1.0.5, if the application calls
png_set_rgb_to_gray()).
png_get_PLTE(png_ptr, info_ptr, &palette,
&num_palette);
palette - the palette for the file
(array of png_color)
src/Source/LibPNG/libpng.3 view on Meta::CPAN
(PNG_INFO_hIST)
hist - histogram of palette (array of
png_uint_16)
png_get_tIME(png_ptr, info_ptr, &mod_time);
mod_time - time image was last modified
(PNG_VALID_tIME)
png_get_bKGD(png_ptr, info_ptr, &background);
background - background color (of type
png_color_16p) (PNG_VALID_bKGD)
valid 16-bit red, green and blue
values, regardless of color_type
num_comments = png_get_text(png_ptr, info_ptr,
&text_ptr, &num_text);
num_comments - number of comments
text_ptr - array of png_text holding image
src/Source/LibPNG/libpng.3 view on Meta::CPAN
Transformations you request are ignored if they don't have any meaning for a
particular input data format. However some transformations can have an effect
as a result of a previous transformation. If you specify a contradictory set of
transformations, for example both adding and removing the alpha channel, you
cannot predict the final result.
The color used for the transparency values should be supplied in the same
format/depth as the current image data. It is stored in the same format/depth
as the image data in a tRNS chunk, so this is what libpng expects for this data.
The color used for the background value depends on the need_expand argument as
described below.
Data will be decoded into the supplied row buffers packed into bytes
unless the library has been told to transform it into another format.
For example, 4 bit/pixel paletted or grayscale data will be returned
2 pixels/byte with the leftmost pixel in the high-order bits of the
byte, unless png_set_packing() is called. 8-bit RGB data will be stored
in RGB RGB RGB format unless png_set_filler() or png_set_add_alpha()
is called to insert filler bytes, either before or after each RGB triplet.
16-bit RGB data will be returned RRGGBB RRGGBB, with the most significant
src/Source/LibPNG/libpng.3 view on Meta::CPAN
If you need to process the alpha channel on the image separately from the image
data (for example if you convert it to a bitmap mask) it is possible to have
libpng strip the channel leaving just RGB or gray data:
if (color_type & PNG_COLOR_MASK_ALPHA)
png_set_strip_alpha(png_ptr);
If you strip the alpha channel you need to find some other way of dealing with
the information. If, instead, you want to convert the image to an opaque
version with no alpha channel use png_set_background; see below.
As of libpng version 1.5.2, almost all useful expansions are supported, the
major ommissions are conversion of grayscale to indexed images (which can be
done trivially in the application) and conversion of indexed to grayscale (which
can be done by a trivial manipulation of the palette.)
In the following table, the 01 means grayscale with depth<8, 31 means
indexed with depth<8, other numerals represent the color type, "T" means
the tRNS chunk is present, A means an alpha channel is present, and O
means tRNS or alpha is present but all pixels in the image are opaque.
src/Source/LibPNG/libpng.3 view on Meta::CPAN
format).
"C" means the transformation is obtained by png_set_gray_to_rgb().
"G" means the transformation is obtained by png_set_rgb_to_gray().
"P" means the transformation is obtained by
png_set_expand_palette_to_rgb().
"p" means the transformation is obtained by png_set_packing().
"Q" means the transformation is obtained by png_set_quantize().
"T" means the transformation is obtained by
png_set_tRNS_to_alpha().
"B" means the transformation is obtained by
png_set_background(), or png_strip_alpha().
When an entry has multiple transforms listed all are required to cause the
right overall transformation. When two transforms are separated by a comma
either will do the job. When transforms are enclosed in [] the transform should
do the job but this is currently unimplemented - a different format will result
if the suggested transformations are used.
In PNG files, the alpha channel in an image
is the level of opacity. If you need the alpha channel in an image to
be the level of transparency instead of opacity, you can invert the
src/Source/LibPNG/libpng.3 view on Meta::CPAN
Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
Libpng uses an integer approximation:
Y = (6968 * R + 23434 * G + 2366 * B)/32768
The calculation is done in a linear colorspace, if the image gamma
can be determined.
The png_set_background() function has been described already; it tells libpng to
composite images with alpha or simple transparency against the supplied
background color. For compatibility with versions of libpng earlier than
libpng-1.5.4 it is recommended that you call the function after reading the file
header, even if you don't want to use the color in a bKGD chunk, if one exists.
If the PNG file contains a bKGD chunk (PNG_INFO_bKGD valid),
you may use this color, or supply another color more suitable for
the current display (e.g., the background color from a web page). You
need to tell libpng how the color is represented, both the format of the
component values in the color (the number of bits) and the gamma encoding of the
color. The function takes two arguments, background_gamma_mode and need_expand
to convey this information; however, only two combinations are likely to be
useful:
png_color_16 my_background;
png_color_16p image_background;
if (png_get_bKGD(png_ptr, info_ptr, &image_background))
png_set_background(png_ptr, image_background,
PNG_BACKGROUND_GAMMA_FILE, 1/*needs to be expanded*/, 1);
else
png_set_background(png_ptr, &my_background,
PNG_BACKGROUND_GAMMA_SCREEN, 0/*do not expand*/, 1);
The second call was described above - my_background is in the format of the
final, display, output produced by libpng. Because you now know the format of
the PNG it is possible to avoid the need to choose either 8-bit or 16-bit
output and to retain palette images (the palette colors will be modified
appropriately and the tRNS chunk removed.) However, if you are doing this,
take great care not to ask for transformations without checking first that
they apply!
In the first call the background color has the original bit depth and color type
of the PNG file. So, for palette images the color is supplied as a palette
index and for low bit greyscale images the color is a reduced bit value in
image_background->gray.
If you didn't call png_set_gamma() before reading the file header, for example
if you need your code to remain compatible with older versions of libpng prior
to libpng-1.5.4, this is the place to call it.
Do not call it if you called png_set_alpha_mode(); doing so will damage the
settings put in place by png_set_alpha_mode(). (If png_set_alpha_mode() is
supported then you can certainly do png_set_gamma() before reading the PNG
header.)
src/Source/LibPNG/libpng.3 view on Meta::CPAN
After setting the transformations, libpng can update your png_info
structure to reflect any transformations you've requested with this
call.
png_read_update_info(png_ptr, info_ptr);
This is most useful to update the info structure's rowbytes
field so you can use it to allocate your image memory. This function
will also update your palette with the correct screen_gamma and
background if these have been given with the calls above. You may
only call png_read_update_info() once with a particular info_ptr.
After you call png_read_update_info(), you can allocate any
memory you need to hold the image. The row data is simply
raw byte data for all forms of images. As the actual allocation
varies among applications, no example will be given. If you
are allocating one large chunk, you will need to build an
array of pointers to each row, as it will be needed for some
of the functions below.
src/Source/LibPNG/libpng.3 view on Meta::CPAN
png_set_hIST(png_ptr, info_ptr, hist);
hist - histogram of palette (array of
png_uint_16) (PNG_INFO_hIST)
png_set_tIME(png_ptr, info_ptr, mod_time);
mod_time - time image was last modified
(PNG_VALID_tIME)
png_set_bKGD(png_ptr, info_ptr, background);
background - background color (of type
png_color_16p) (PNG_VALID_bKGD)
png_set_text(png_ptr, info_ptr, text_ptr, num_text);
text_ptr - array of png_text holding image
comments
text_ptr[i].compression - type of compression used
on "text" PNG_TEXT_COMPRESSION_NONE
PNG_TEXT_COMPRESSION_zTXt
src/Source/LibPNG/libpng.3 view on Meta::CPAN
FILE* file)
The PNG header is read from the stdio FILE object.
int png_image_begin_read_from_memory(png_imagep image,
png_const_voidp memory, png_size_t size)
The PNG header is read from the given memory buffer.
int png_image_finish_read(png_imagep image,
png_colorp background, void *buffer,
png_int_32 row_stride, void *colormap));
Finish reading the image into the supplied buffer and
clean up the png_image structure.
row_stride is the step, in png_byte or png_uint_16 units
as appropriate, between adjacent rows. A positive stride
indicates that the top-most row is first in the buffer -
the normal top-down arrangement. A negative stride
indicates that the bottom-most row is first in the buffer.
background need only be supplied if an alpha channel must
be removed from a png_byte format and the removal is to be
done by compositing on a solid color; otherwise it may be
NULL and any composition will be done directly onto the
buffer. The value is an sRGB color to use for the
background, for grayscale output the green channel is used.
For linear output removing the alpha channel is always done
by compositing on black.
void png_image_free(png_imagep image)
Free any data allocated by libpng in image->opaque,
setting the pointer to NULL. May be called at any time
after the structure is initialized.
src/Source/LibPNG/libpng.3 view on Meta::CPAN
libpng 1.5.0 includes a complete fixed point API. By default this is
present along with the corresponding floating point API. In general the
fixed point API is faster and smaller than the floating point one because
the PNG file format used fixed point, not floating point. This applies
even if the library uses floating point in internal calculations. A new
macro, PNG_FLOATING_ARITHMETIC_SUPPORTED, reveals whether the library
uses floating point arithmetic (the default) or fixed point arithmetic
internally for performance critical calculations such as gamma correction.
In some cases, the gamma calculations may produce slightly different
results. This has changed the results in png_rgb_to_gray and in alpha
composition (png_set_background for example). This applies even if the
original image was already linear (gamma == 1.0) and, therefore, it is
not necessary to linearize the image. This is because libpng has *not*
been changed to optimize that case correctly, yet.
Fixed point support for the sCAL chunk comes with an important caveat;
the sCAL specification uses a decimal encoding of floating point values
and the accuracy of PNG fixed point values is insufficient for
representation of these values. Consequently a "string" API
(png_get_sCAL_s and png_set_sCAL_s) is the only reliable way of reading
arbitrary sCAL chunks in the absence of either the floating point API or
src/Source/LibPNG/libpng.3 view on Meta::CPAN
are allowed by the PNG specification, so these warnings are no longer issued.
The library now issues an error if the application attempts to set a
transform after it calls png_read_update_info() or if it attempts to call
both png_read_update_info() and png_start_read_image() or to call either
of them more than once.
The default condition for benign_errors is now to treat benign errors as
warnings while reading and as errors while writing.
The library now issues a warning if both background processing and RGB to
gray are used when gamma correction happens. As with previous versions of
the library the results are numerically very incorrect in this case.
There are some minor arithmetic changes in some transforms such as
png_set_background(), that might be detected by certain regression tests.
Unknown chunk handling has been improved internally, without any API change.
This adds more correct option control of the unknown handling, corrects
a pre-existing bug where the per-chunk 'keep' setting is ignored, and makes
it possible to skip IDAT chunks in the sequential reader.
The machine-generated configure files are no longer included in branches
libpng16 and later of the GIT repository. They continue to be included
in the tarball releases, however.
src/Source/LibPNG/png.c view on Meta::CPAN
#endif /* iCCP */
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
void /* PRIVATE */
png_colorspace_set_rgb_coefficients(png_structrp png_ptr)
{
/* Set the rgb_to_gray coefficients from the colorspace. */
if (png_ptr->rgb_to_gray_coefficients_set == 0 &&
(png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
{
/* png_set_background has not been called, get the coefficients from the Y
* values of the colorspace colorants.
*/
png_fixed_point r = png_ptr->colorspace.end_points_XYZ.red_Y;
png_fixed_point g = png_ptr->colorspace.end_points_XYZ.green_Y;
png_fixed_point b = png_ptr->colorspace.end_points_XYZ.blue_Y;
png_fixed_point total = r+g+b;
if (total > 0 &&
r >= 0 && png_muldiv(&r, r, 32768, total) && r >= 0 && r <= 32768 &&
g >= 0 && png_muldiv(&g, g, 32768, total) && g >= 0 && g <= 32768 &&
src/Source/LibPNG/png.c view on Meta::CPAN
if (shift < (16U - PNG_MAX_GAMMA_8))
shift = (16U - PNG_MAX_GAMMA_8);
}
if (shift > 8U)
shift = 8U; /* Guarantees at least one table! */
png_ptr->gamma_shift = shift;
/* NOTE: prior to 1.5.4 this test used to include PNG_BACKGROUND (now
* PNG_COMPOSE). This effectively smashed the background calculation for
* 16-bit output because the 8-bit table assumes the result will be reduced
* to 8 bits.
*/
if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0)
png_build_16to8_table(png_ptr, &png_ptr->gamma_16_table, shift,
png_ptr->screen_gamma > 0 ? png_product2(png_ptr->colorspace.gamma,
png_ptr->screen_gamma) : PNG_FP_1);
else
png_build_16bit_table(png_ptr, &png_ptr->gamma_16_table, shift,
src/Source/LibPNG/png.h view on Meta::CPAN
* png_set_expand_16(pp);
* png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_DEFAULT_sRGB);
* This is a somewhat more realistic Jim Blinn inspired approach. PNG files
* are assumed to have the sRGB encoding if not marked with a gamma value and
* the output is always 16 bits per component. This permits accurate scaling
* and processing of the data. If you know that your input PNG files were
* generated locally you might need to replace PNG_DEFAULT_sRGB with the
* correct value for your system.
*
* png_set_alpha_mode(pp, PNG_ALPHA_OPTIMIZED, PNG_DEFAULT_sRGB);
* If you just need to composite the PNG image onto an existing background
* and if you control the code that does this you can use the optimization
* setting. In this case you just copy completely opaque pixels to the
* output. For pixels that are not completely transparent (you just skip
* those) you do the composition math using png_composite or png_composite_16
* below then encode the resultant 8-bit or 16-bit values to match the output
* encoding.
*
* Other cases
* If neither the PNG nor the standard linear encoding work for you because
* of the software or hardware you use then you have a big problem. The PNG
* case will probably result in halos around the image. The linear encoding
* will probably result in a washed out, too bright, image (it's actually too
* contrasty.) Try the ALPHA_OPTIMIZED mode above - this will probably
* substantially reduce the halos. Alternatively try:
*
* png_set_alpha_mode(pp, PNG_ALPHA_BROKEN, PNG_DEFAULT_sRGB);
* This option will also reduce the halos, but there will be slight dark
* halos round the opaque parts of the image where the background is light.
* In the OPTIMIZED mode the halos will be light halos where the background
* is dark. Take your pick - the halos are unavoidable unless you can get
* your hardware/software fixed! (The OPTIMIZED approach is slightly
* faster.)
*
* When the default gamma of PNG files doesn't match the output gamma.
* If you have PNG files with no gamma information png_set_alpha_mode allows
* you to provide a default gamma, but it also sets the ouput gamma to the
* matching value. If you know your PNG files have a gamma that doesn't
* match the output you can take advantage of the fact that
* png_set_alpha_mode always sets the output gamma but only sets the PNG
* default if it is not already set:
*
* png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
* png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
* The first call sets both the default and the output gamma values, the
* second call overrides the output gamma without changing the default. This
* is easier than achieving the same effect with png_set_gamma. You must use
* PNG_ALPHA_PNG for the first call - internal checking in png_set_alpha will
* fire if more than one call to png_set_alpha_mode and png_set_background is
* made in the same read operation, however multiple calls with PNG_ALPHA_PNG
* are ignored.
*/
#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
PNG_EXPORT(36, void, png_set_strip_alpha, (png_structrp png_ptr));
#endif
#if defined(PNG_READ_SWAP_ALPHA_SUPPORTED) || \
defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
src/Source/LibPNG/png.h view on Meta::CPAN
*/
PNG_EXPORT(45, int, png_set_interlace_handling, (png_structrp png_ptr));
#endif
#if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
/* Invert monochrome files */
PNG_EXPORT(46, void, png_set_invert_mono, (png_structrp png_ptr));
#endif
#ifdef PNG_READ_BACKGROUND_SUPPORTED
/* Handle alpha and tRNS by replacing with a background color. Prior to
* libpng-1.5.4 this API must not be called before the PNG file header has been
* read. Doing so will result in unexpected behavior and possible warnings or
* errors if the PNG file contains a bKGD chunk.
*/
PNG_FP_EXPORT(47, void, png_set_background, (png_structrp png_ptr,
png_const_color_16p background_color, int background_gamma_code,
int need_expand, double background_gamma))
PNG_FIXED_EXPORT(215, void, png_set_background_fixed, (png_structrp png_ptr,
png_const_color_16p background_color, int background_gamma_code,
int need_expand, png_fixed_point background_gamma))
#endif
#ifdef PNG_READ_BACKGROUND_SUPPORTED
# define PNG_BACKGROUND_GAMMA_UNKNOWN 0
# define PNG_BACKGROUND_GAMMA_SCREEN 1
# define PNG_BACKGROUND_GAMMA_FILE 2
# define PNG_BACKGROUND_GAMMA_UNIQUE 3
#endif
#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
/* Scale a 16-bit depth file down to 8-bit, accurately. */
src/Source/LibPNG/png.h view on Meta::CPAN
#endif /* EASY_ACCESS */
#ifdef PNG_READ_SUPPORTED
/* Returns pointer to signature string read from PNG header */
PNG_EXPORT(130, png_const_bytep, png_get_signature, (png_const_structrp png_ptr,
png_const_inforp info_ptr));
#endif
#ifdef PNG_bKGD_SUPPORTED
PNG_EXPORT(131, png_uint_32, png_get_bKGD, (png_const_structrp png_ptr,
png_inforp info_ptr, png_color_16p *background));
#endif
#ifdef PNG_bKGD_SUPPORTED
PNG_EXPORT(132, void, png_set_bKGD, (png_const_structrp png_ptr,
png_inforp info_ptr, png_const_color_16p background));
#endif
#ifdef PNG_cHRM_SUPPORTED
PNG_FP_EXPORT(133, png_uint_32, png_get_cHRM, (png_const_structrp png_ptr,
png_const_inforp info_ptr, double *white_x, double *white_y, double *red_x,
double *red_y, double *green_x, double *green_y, double *blue_x,
double *blue_y))
PNG_FP_EXPORT(230, png_uint_32, png_get_cHRM_XYZ, (png_const_structrp png_ptr,
png_const_inforp info_ptr, double *red_X, double *red_Y, double *red_Z,
double *green_X, double *green_Y, double *green_Z, double *blue_X,
src/Source/LibPNG/png.h view on Meta::CPAN
PNG_EXPORT(235, int, png_image_begin_read_from_stdio, (png_imagep image,
FILE* file));
/* The PNG header is read from the stdio FILE object. */
#endif /* STDIO */
PNG_EXPORT(236, int, png_image_begin_read_from_memory, (png_imagep image,
png_const_voidp memory, png_size_t size));
/* The PNG header is read from the given memory buffer. */
PNG_EXPORT(237, int, png_image_finish_read, (png_imagep image,
png_const_colorp background, void *buffer, png_int_32 row_stride,
void *colormap));
/* Finish reading the image into the supplied buffer and clean up the
* png_image structure.
*
* row_stride is the step, in byte or 2-byte units as appropriate,
* between adjacent rows. A positive stride indicates that the top-most row
* is first in the buffer - the normal top-down arrangement. A negative
* stride indicates that the bottom-most row is first in the buffer.
*
* background need only be supplied if an alpha channel must be removed from
* a png_byte format and the removal is to be done by compositing on a solid
* color; otherwise it may be NULL and any composition will be done directly
* onto the buffer. The value is an sRGB color to use for the background,
* for grayscale output the green channel is used.
*
* background must be supplied when an alpha channel must be removed from a
* single byte color-mapped output format, in other words if:
*
* 1) The original format from png_image_begin_read_from_* had
* PNG_FORMAT_FLAG_ALPHA set.
* 2) The format set by the application does not.
* 3) The format set by the application has PNG_FORMAT_FLAG_COLORMAP set and
* PNG_FORMAT_FLAG_LINEAR *not* set.
*
* For linear output removing the alpha channel is always done by compositing
* on black and background is ignored.
*
* colormap must be supplied when PNG_FORMAT_FLAG_COLORMAP is set. It must
* be at least the size (in bytes) returned by PNG_IMAGE_COLORMAP_SIZE.
* image->colormap_entries will be updated to the actual number of entries
* written to the colormap; this may be less than the original value.
*/
PNG_EXPORT(238, void, png_image_free, (png_imagep image));
/* Free any data allocated by libpng in image->opaque, setting the pointer to
* NULL. May be called at any time after the structure is initialized.
src/Source/LibPNG/pngget.c view on Meta::CPAN
if (png_ptr != NULL && info_ptr != NULL)
return(info_ptr->signature);
return (NULL);
}
#endif
#ifdef PNG_bKGD_SUPPORTED
png_uint_32 PNGAPI
png_get_bKGD(png_const_structrp png_ptr, png_inforp info_ptr,
png_color_16p *background)
{
if (png_ptr != NULL && info_ptr != NULL &&
(info_ptr->valid & PNG_INFO_bKGD) != 0 &&
background != NULL)
{
png_debug1(1, "in %s retrieval function", "bKGD");
*background = &(info_ptr->background);
return (PNG_INFO_bKGD);
}
return (0);
}
#endif
#ifdef PNG_cHRM_SUPPORTED
/* The XYZ APIs were added in 1.5.5 to take advantage of the code added at the
* same time to correct the rgb grayscale coefficient defaults obtained from the
src/Source/LibPNG/pnginfo.h view on Meta::CPAN
* for the data are in the range [0, 255], ranging from fully transparent
* to fully opaque, respectively. For non-paletted images, there is a
* single color specified that should be treated as fully transparent.
* Data is valid if (valid & PNG_INFO_tRNS) is non-zero.
*/
png_bytep trans_alpha; /* alpha values for paletted image */
png_color_16 trans_color; /* transparent color for non-palette image */
#endif
#if defined(PNG_bKGD_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
/* The bKGD chunk gives the suggested image background color if the
* display program does not have its own background color and the image
* is needs to composited onto a background before display. The colors
* in "background" are normally in the same color space/depth as the
* pixel data. Data is valid if (valid & PNG_INFO_bKGD) is non-zero.
*/
png_color_16 background;
#endif
#ifdef PNG_oFFs_SUPPORTED
/* The oFFs chunk gives the offset in "offset_unit_type" units rightwards
* and downwards from the top-left corner of the display, page, or other
* application-specific co-ordinate space. See the PNG_OFFSET_ defines
* below for the unit types. Valid if (valid & PNG_INFO_oFFs) non-zero.
*/
png_int_32 x_offset; /* x offset on page */
png_int_32 y_offset; /* y offset on page */
src/Source/LibPNG/pngread.c view on Meta::CPAN
}
/* New in 1.6.0 this avoids the bug of doing the initializations twice */
else
png_app_error(png_ptr,
"png_read_update_info/png_start_read_image: duplicate call");
}
}
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Initialize palette, background, etc, after transformations
* are set, but before any reading takes place. This allows
* the user to obtain a gamma-corrected palette, for example.
* If the user doesn't call this, we will do it ourselves.
*/
void PNGAPI
png_start_read_image(png_structrp png_ptr)
{
png_debug(1, "in png_start_read_image");
if (png_ptr != NULL)
src/Source/LibPNG/pngread.c view on Meta::CPAN
* which is supported to get the right answer.
*/
if ((transforms & PNG_TRANSFORM_STRIP_16) != 0)
#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
png_set_strip_16(png_ptr);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_16 not supported");
#endif
/* Strip alpha bytes from the input data without combining with
* the background (not recommended).
*/
if ((transforms & PNG_TRANSFORM_STRIP_ALPHA) != 0)
#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
png_set_strip_alpha(png_ptr);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_ALPHA not supported");
#endif
/* Extract multiple pixels with bit depths of 1, 2, or 4 from a single
* byte into separate bytes (useful for paletted and grayscale images).
src/Source/LibPNG/pngread.c view on Meta::CPAN
* Expand paletted or RGB images with transparency to full alpha
* channels so the data will be available as RGBA quartets.
*/
if ((transforms & PNG_TRANSFORM_EXPAND) != 0)
#ifdef PNG_READ_EXPAND_SUPPORTED
png_set_expand(png_ptr);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND not supported");
#endif
/* We don't handle background color or gamma transformation or quantizing.
*/
/* Invert monochrome files to have 0 as white and 1 as black
*/
if ((transforms & PNG_TRANSFORM_INVERT_MONO) != 0)
#ifdef PNG_READ_INVERT_SUPPORTED
png_set_invert_mono(png_ptr);
#else
png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_MONO not supported");
#endif
src/Source/LibPNG/pngread.c view on Meta::CPAN
png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND_16 not supported");
#endif
/* We don't handle adding filler bytes */
/* We use png_read_image and rely on that for interlace handling, but we also
* call png_read_update_info therefore must turn on interlace handling now:
*/
(void)png_set_interlace_handling(png_ptr);
/* Optional call to gamma correct and add the background to the palette
* and update info structure. REQUIRED if you are expecting libpng to
* update the palette for you (i.e., you selected such a transform above).
*/
png_read_update_info(png_ptr, info_ptr);
/* -------------- image transformations end here ------------------- */
png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0);
if (info_ptr->row_pointers == NULL)
{
src/Source/LibPNG/pngread.c view on Meta::CPAN
# define P_sRGB 1 /* 8-bit encoded to sRGB gamma */
# define P_LINEAR 2 /* 16-bit linear: not encoded, NOT pre-multiplied! */
# define P_FILE 3 /* 8-bit encoded to file gamma, not sRGB or linear */
# define P_LINEAR8 4 /* 8-bit linear: only from a file value */
/* Color-map processing: after libpng has run on the PNG image further
* processing may be needed to convert the data to color-map indices.
*/
#define PNG_CMAP_NONE 0
#define PNG_CMAP_GA 1 /* Process GA data to a color-map with alpha */
#define PNG_CMAP_TRANS 2 /* Process GA data to a background index */
#define PNG_CMAP_RGB 3 /* Process RGB data */
#define PNG_CMAP_RGB_ALPHA 4 /* Process RGBA data */
/* The following document where the background is for each processing case. */
#define PNG_CMAP_NONE_BACKGROUND 256
#define PNG_CMAP_GA_BACKGROUND 231
#define PNG_CMAP_TRANS_BACKGROUND 254
#define PNG_CMAP_RGB_BACKGROUND 256
#define PNG_CMAP_RGB_ALPHA_BACKGROUND 216
typedef struct
{
/* Arguments: */
png_imagep image;
png_voidp buffer;
png_int_32 row_stride;
png_voidp colormap;
png_const_colorp background;
/* Local variables: */
png_voidp local_row;
png_voidp first_row;
ptrdiff_t row_bytes; /* step between rows */
int file_encoding; /* E_ values above */
png_fixed_point gamma_to_linear; /* For P_FILE, reciprocal of gamma */
int colormap_processing; /* PNG_CMAP_ values above */
} png_image_read_control;
/* Do all the *safe* initialization - 'safe' means that png_error won't be
src/Source/LibPNG/pngread.c view on Meta::CPAN
"unexpected encoding (internal error)");
break;
}
return value;
}
static png_uint_32
png_colormap_compose(png_image_read_control *display,
png_uint_32 foreground, int foreground_encoding, png_uint_32 alpha,
png_uint_32 background, int encoding)
{
/* The file value is composed on the background, the background has the given
* encoding and so does the result, the file is encoded with P_FILE and the
* file and alpha are 8-bit values. The (output) encoding will always be
* P_LINEAR or P_sRGB.
*/
png_uint_32 f = decode_gamma(display, foreground, foreground_encoding);
png_uint_32 b = decode_gamma(display, background, encoding);
/* The alpha is always an 8-bit value (it comes from the palette), the value
* scaled by 255 is what PNG_sRGB_FROM_LINEAR requires.
*/
f = f * alpha + b * (255-alpha);
if (encoding == P_LINEAR)
{
/* Scale to 65535; divide by 255, approximately (in fact this is extremely
* accurate, it divides by 255.00000005937181414556, with no overflow.)
src/Source/LibPNG/pngread.c view on Meta::CPAN
const png_structrp png_ptr = image->opaque->png_ptr;
const png_uint_32 output_format = image->format;
const int output_encoding = (output_format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
P_LINEAR : P_sRGB;
unsigned int cmap_entries;
unsigned int output_processing; /* Output processing option */
unsigned int data_encoding = P_NOTSET; /* Encoding libpng must produce */
/* Background information; the background color and the index of this color
* in the color-map if it exists (else 256).
*/
unsigned int background_index = 256;
png_uint_32 back_r, back_g, back_b;
/* Flags to accumulate things that need to be done to the input. */
int expand_tRNS = 0;
/* Exclude the NYI feature of compositing onto a color-mapped buffer; it is
* very difficult to do, the results look awful, and it is difficult to see
* what possible use it is because the application can't control the
* color-map.
*/
if (((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0 ||
png_ptr->num_trans > 0) /* alpha in input */ &&
((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) /* no alpha in output */)
{
if (output_encoding == P_LINEAR) /* compose on black */
back_b = back_g = back_r = 0;
else if (display->background == NULL /* no way to remove it */)
png_error(png_ptr,
"a background color must be supplied to remove alpha/transparency");
/* Get a copy of the background color (this avoids repeating the checks
* below.) The encoding is 8-bit sRGB or 16-bit linear, depending on the
* output format.
*/
else
{
back_g = display->background->green;
if ((output_format & PNG_FORMAT_FLAG_COLOR) != 0)
{
back_r = display->background->red;
back_b = display->background->blue;
}
else
back_b = back_r = back_g;
}
}
else if (output_encoding == P_LINEAR)
back_b = back_r = back_g = 65535;
else
src/Source/LibPNG/pngread.c view on Meta::CPAN
unsigned int step, i, val, trans = 256/*ignore*/, back_alpha = 0;
cmap_entries = 1U << png_ptr->bit_depth;
if (cmap_entries > image->colormap_entries)
png_error(png_ptr, "gray[8] color-map: too few entries");
step = 255 / (cmap_entries - 1);
output_processing = PNG_CMAP_NONE;
/* If there is a tRNS chunk then this either selects a transparent
* value or, if the output has no alpha, the background color.
*/
if (png_ptr->num_trans > 0)
{
trans = png_ptr->trans_color.gray;
if ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0)
back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
}
/* png_create_colormap_entry just takes an RGBA and writes the
src/Source/LibPNG/pngread.c view on Meta::CPAN
if (i != trans)
png_create_colormap_entry(display, i, val, val, val, 255,
P_FILE/*8-bit with file gamma*/);
/* Else this entry is transparent. The colors don't matter if
* there is an alpha channel (back_alpha == 0), but it does no
* harm to pass them in; the values are not set above so this
* passes in white.
*
* NOTE: this preserves the full precision of the application
* supplied background color when it is used.
*/
else
png_create_colormap_entry(display, i, back_r, back_g, back_b,
back_alpha, output_encoding);
}
/* We need libpng to preserve the original encoding. */
data_encoding = P_FILE;
/* The rows from libpng, while technically gray values, are now also
src/Source/LibPNG/pngread.c view on Meta::CPAN
* encoded values; however, if a tRNS chunk is present 257 color-map
* entries are required. This means that the extra entry requires
* special processing; add an alpha channel, sacrifice gray level
* 254 and convert transparent (alpha==0) entries to that.
*
* Use libpng to chop the data to 8 bits. Convert it to sRGB at the
* same time to minimize quality loss. If a tRNS chunk is present
* this means libpng must handle it too; otherwise it is impossible
* to do the exact match on the 16-bit value.
*
* If the output has no alpha channel *and* the background color is
* gray then it is possible to let libpng handle the substitution by
* ensuring that the corresponding gray level matches the background
* color exactly.
*/
data_encoding = P_sRGB;
if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
png_error(png_ptr, "gray[16] color-map: too few entries");
cmap_entries = make_gray_colormap(display);
if (png_ptr->num_trans > 0)
src/Source/LibPNG/pngread.c view on Meta::CPAN
{
gray = PNG_sRGB_FROM_LINEAR(gray * 255);
/* And make sure the corresponding palette entry
* matches.
*/
png_create_colormap_entry(display, gray, back_g, back_g,
back_g, 65535, P_LINEAR);
}
/* The background passed to libpng, however, must be the
* sRGB value.
*/
c.index = 0; /*unused*/
c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
/* NOTE: does this work without expanding tRNS to alpha?
* It should be the color->gray case below apparently
* doesn't.
*/
png_set_background_fixed(png_ptr, &c,
PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
0/*gamma: not used*/);
output_processing = PNG_CMAP_NONE;
break;
}
back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
}
/* output_processing means that the libpng-processed row will be
* 8-bit GA and it has to be processing to single byte color-map
* values. Entry 254 is replaced by either a completely
* transparent entry or by the background color at full
* precision (and the background color is not a simple gray
* level in this case.)
*/
expand_tRNS = 1;
output_processing = PNG_CMAP_TRANS;
background_index = 254;
/* And set (overwrite) color-map entry 254 to the actual
* background color at full precision.
*/
png_create_colormap_entry(display, 254, back_r, back_g, back_b,
back_alpha, output_encoding);
}
else
output_processing = PNG_CMAP_NONE;
}
break;
case PNG_COLOR_TYPE_GRAY_ALPHA:
/* 8-bit or 16-bit PNG with two channels - gray and alpha. A minimum
* of 65536 combinations. If, however, the alpha channel is to be
* removed there are only 256 possibilities if the background is gray.
* (Otherwise there is a subset of the 65536 possibilities defined by
* the triangle between black, white and the background color.)
*
* Reduce 16-bit files to 8-bit and sRGB encode the result. No need to
* worry about tRNS matching - tRNS is ignored if there is an alpha
* channel.
*/
data_encoding = P_sRGB;
if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
{
if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
png_error(png_ptr, "gray+alpha color-map: too few entries");
cmap_entries = make_ga_colormap(display);
background_index = PNG_CMAP_GA_BACKGROUND;
output_processing = PNG_CMAP_GA;
}
else /* alpha is removed */
{
/* Alpha must be removed as the PNG data is processed when the
* background is a color because the G and A channels are
* independent and the vector addition (non-parallel vectors) is a
* 2-D problem.
*
* This can be reduced to the same algorithm as above by making a
* colormap containing gray levels (for the opaque grays), a
* background entry (for a transparent pixel) and a set of four six
* level color values, one set for each intermediate alpha value.
* See the comments in make_ga_colormap for how this works in the
* per-pixel processing.
*
* If the background is gray, however, we only need a 256 entry gray
* level color map. It is sufficient to make the entry generated
* for the background color be exactly the color specified.
*/
if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0 ||
(back_r == back_g && back_g == back_b))
{
/* Background is gray; no special processing will be required. */
png_color_16 c;
png_uint_32 gray = back_g;
if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
png_error(png_ptr, "gray-alpha color-map: too few entries");
src/Source/LibPNG/pngread.c view on Meta::CPAN
if (output_encoding == P_LINEAR)
{
gray = PNG_sRGB_FROM_LINEAR(gray * 255);
/* And make sure the corresponding palette entry matches. */
png_create_colormap_entry(display, gray, back_g, back_g,
back_g, 65535, P_LINEAR);
}
/* The background passed to libpng, however, must be the sRGB
* value.
*/
c.index = 0; /*unused*/
c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
png_set_background_fixed(png_ptr, &c,
PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
0/*gamma: not used*/);
output_processing = PNG_CMAP_NONE;
}
else
{
png_uint_32 i, a;
src/Source/LibPNG/pngread.c view on Meta::CPAN
i = 0;
while (i < 231)
{
png_uint_32 gray = (i * 256 + 115) / 231;
png_create_colormap_entry(display, i++, gray, gray, gray,
255, P_sRGB);
}
/* NOTE: this preserves the full precision of the application
* background color.
*/
background_index = i;
png_create_colormap_entry(display, i++, back_r, back_g, back_b,
output_encoding == P_LINEAR ? 65535U : 255U, output_encoding);
/* For non-opaque input composite on the sRGB background - this
* requires inverting the encoding for each component. The input
* is still converted to the sRGB encoding because this is a
* reasonable approximate to the logarithmic curve of human
* visual sensitivity, at least over the narrow range which PNG
* represents. Consequently 'G' is always sRGB encoded, while
* 'A' is linear. We need the linear background colors.
*/
if (output_encoding == P_sRGB) /* else already linear */
{
/* This may produce a value not exactly matching the
* background, but that's ok because these numbers are only
* used when alpha != 0
*/
back_r = png_sRGB_table[back_r];
back_g = png_sRGB_table[back_g];
back_b = png_sRGB_table[back_b];
}
for (a=1; a<5; ++a)
{
unsigned int g;
src/Source/LibPNG/pngread.c view on Meta::CPAN
/* Exclude the case where the output is gray; we can always handle this
* with the cases above.
*/
if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0)
{
/* The color-map will be grayscale, so we may as well convert the
* input RGB values to a simple grayscale and use the grayscale
* code above.
*
* NOTE: calling this apparently damages the recognition of the
* transparent color in background color handling; call
* png_set_tRNS_to_alpha before png_set_background_fixed.
*/
png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, -1,
-1);
data_encoding = P_sRGB;
/* The output will now be one or two 8-bit gray or gray+alpha
* channels. The more complex case arises when the input has alpha.
*/
if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
png_ptr->num_trans > 0) &&
(output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
{
/* Both input and output have an alpha channel, so no background
* processing is required; just map the GA bytes to the right
* color-map entry.
*/
expand_tRNS = 1;
if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
png_error(png_ptr, "rgb[ga] color-map: too few entries");
cmap_entries = make_ga_colormap(display);
background_index = PNG_CMAP_GA_BACKGROUND;
output_processing = PNG_CMAP_GA;
}
else
{
/* Either the input or the output has no alpha channel, so there
* will be no non-opaque pixels in the color-map; it will just be
* grayscale.
*/
if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
src/Source/LibPNG/pngread.c view on Meta::CPAN
cmap_entries = make_gray_colormap(display);
/* But if the input has alpha or transparency it must be removed
*/
if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
png_ptr->num_trans > 0)
{
png_color_16 c;
png_uint_32 gray = back_g;
/* We need to ensure that the application background exists in
* the colormap and that completely transparent pixels map to
* it. Achieve this simply by ensuring that the entry
* selected for the background really is the background color.
*/
if (data_encoding == P_FILE) /* from the fixup above */
{
/* The app supplied a gray which is in output_encoding, we
* need to convert it to a value of the input (P_FILE)
* encoding then set this palette entry to the required
* output encoding.
*/
if (output_encoding == P_sRGB)
gray = png_sRGB_table[gray]; /* now P_LINEAR */
src/Source/LibPNG/pngread.c view on Meta::CPAN
else if (output_encoding == P_LINEAR)
{
gray = PNG_sRGB_FROM_LINEAR(gray * 255);
/* And make sure the corresponding palette entry matches.
*/
png_create_colormap_entry(display, gray, back_g, back_g,
back_g, 0/*unused*/, P_LINEAR);
}
/* The background passed to libpng, however, must be the
* output (normally sRGB) value.
*/
c.index = 0; /*unused*/
c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
/* NOTE: the following is apparently a bug in libpng. Without
* it the transparent color recognition in
* png_set_background_fixed seems to go wrong.
*/
expand_tRNS = 1;
png_set_background_fixed(png_ptr, &c,
PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
0/*gamma: not used*/);
}
output_processing = PNG_CMAP_NONE;
}
}
else /* output is color */
{
src/Source/LibPNG/pngread.c view on Meta::CPAN
if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
png_error(png_ptr, "rgb+alpha color-map: too few entries");
cmap_entries = make_rgb_colormap(display);
/* Add a transparent entry. */
png_create_colormap_entry(display, cmap_entries, 255, 255,
255, 0, P_sRGB);
/* This is stored as the background index for the processing
* algorithm.
*/
background_index = cmap_entries++;
/* Add 27 r,g,b entries each with alpha 0.5. */
for (r=0; r<256; r = (r << 1) | 0x7f)
{
png_uint_32 g;
for (g=0; g<256; g = (g << 1) | 0x7f)
{
png_uint_32 b;
src/Source/LibPNG/pngread.c view on Meta::CPAN
r, g, b, 128, P_sRGB);
}
}
expand_tRNS = 1;
output_processing = PNG_CMAP_RGB_ALPHA;
}
else
{
/* Alpha/transparency must be removed. The background must
* exist in the color map (achieved by setting adding it after
* the 666 color-map). If the standard processing code will
* pick up this entry automatically that's all that is
* required; libpng can be called to do the background
* processing.
*/
unsigned int sample_size =
PNG_IMAGE_SAMPLE_SIZE(output_format);
png_uint_32 r, g, b; /* sRGB background */
if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
png_error(png_ptr, "rgb-alpha color-map: too few entries");
cmap_entries = make_rgb_colormap(display);
png_create_colormap_entry(display, cmap_entries, back_r,
back_g, back_b, 0/*unused*/, output_encoding);
if (output_encoding == P_LINEAR)
src/Source/LibPNG/pngread.c view on Meta::CPAN
else
{
r = back_r;
g = back_g;
b = back_g;
}
/* Compare the newly-created color-map entry with the one the
* PNG_CMAP_RGB algorithm will use. If the two entries don't
* match, add the new one and set this as the background
* index.
*/
if (memcmp((png_const_bytep)display->colormap +
sample_size * cmap_entries,
(png_const_bytep)display->colormap +
sample_size * PNG_RGB_INDEX(r,g,b),
sample_size) != 0)
{
/* The background color must be added. */
background_index = cmap_entries++;
/* Add 27 r,g,b entries each with created by composing with
* the background at alpha 0.5.
*/
for (r=0; r<256; r = (r << 1) | 0x7f)
{
for (g=0; g<256; g = (g << 1) | 0x7f)
{
/* This generates components with the values 0, 127
* and 255
*/
for (b=0; b<256; b = (b << 1) | 0x7f)
png_create_colormap_entry(display, cmap_entries++,
src/Source/LibPNG/pngread.c view on Meta::CPAN
png_colormap_compose(display, b, P_sRGB, 128,
back_b, output_encoding),
0/*unused*/, output_encoding);
}
}
expand_tRNS = 1;
output_processing = PNG_CMAP_RGB_ALPHA;
}
else /* background color is in the standard color-map */
{
png_color_16 c;
c.index = 0; /*unused*/
c.red = (png_uint_16)back_r;
c.gray = c.green = (png_uint_16)back_g;
c.blue = (png_uint_16)back_b;
png_set_background_fixed(png_ptr, &c,
PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
0/*gamma: not used*/);
output_processing = PNG_CMAP_RGB;
}
}
}
else /* no alpha or transparency in the input */
{
src/Source/LibPNG/pngread.c view on Meta::CPAN
break;
case PNG_COLOR_TYPE_PALETTE:
/* It's already got a color-map. It may be necessary to eliminate the
* tRNS entries though.
*/
{
unsigned int num_trans = png_ptr->num_trans;
png_const_bytep trans = num_trans > 0 ? png_ptr->trans_alpha : NULL;
png_const_colorp colormap = png_ptr->palette;
const int do_background = trans != NULL &&
(output_format & PNG_FORMAT_FLAG_ALPHA) == 0;
unsigned int i;
/* Just in case: */
if (trans == NULL)
num_trans = 0;
output_processing = PNG_CMAP_NONE;
data_encoding = P_FILE; /* Don't change from color-map indices */
cmap_entries = png_ptr->num_palette;
if (cmap_entries > 256)
cmap_entries = 256;
if (cmap_entries > image->colormap_entries)
png_error(png_ptr, "palette color-map: too few entries");
for (i=0; i < cmap_entries; ++i)
{
if (do_background != 0 && i < num_trans && trans[i] < 255)
{
if (trans[i] == 0)
png_create_colormap_entry(display, i, back_r, back_g,
back_b, 0, output_encoding);
else
{
/* Must compose the PNG file color in the color-map entry
* on the sRGB color in 'back'.
*/
src/Source/LibPNG/pngread.c view on Meta::CPAN
if (png_ptr->bit_depth > 8)
png_set_scale_16(png_ptr);
break;
}
if (cmap_entries > 256 || cmap_entries > image->colormap_entries)
png_error(png_ptr, "color map overflow (BAD internal error)");
image->colormap_entries = cmap_entries;
/* Double check using the recorded background index */
switch (output_processing)
{
case PNG_CMAP_NONE:
if (background_index != PNG_CMAP_NONE_BACKGROUND)
goto bad_background;
break;
case PNG_CMAP_GA:
if (background_index != PNG_CMAP_GA_BACKGROUND)
goto bad_background;
break;
case PNG_CMAP_TRANS:
if (background_index >= cmap_entries ||
background_index != PNG_CMAP_TRANS_BACKGROUND)
goto bad_background;
break;
case PNG_CMAP_RGB:
if (background_index != PNG_CMAP_RGB_BACKGROUND)
goto bad_background;
break;
case PNG_CMAP_RGB_ALPHA:
if (background_index != PNG_CMAP_RGB_ALPHA_BACKGROUND)
goto bad_background;
break;
default:
png_error(png_ptr, "bad processing option (internal error)");
bad_background:
png_error(png_ptr, "bad background index (internal error)");
}
display->colormap_processing = output_processing;
return 1/*ok*/;
}
/* The final part of the color-map read called from png_image_finish_read. */
static int
png_image_read_and_map(png_voidp argument)
src/Source/LibPNG/pngread.c view on Meta::CPAN
inrow += channels+1; /* components and alpha channel */
}
}
}
}
return 1;
}
/* The do_local_background case; called when all the following transforms are to
* be done:
*
* PNG_RGB_TO_GRAY
* PNG_COMPOSITE
* PNG_GAMMA
*
* This is a work-around for the fact that both the PNG_RGB_TO_GRAY and
* PNG_COMPOSITE code performs gamma correction, so we get double gamma
* correction. The fix-up is to prevent the PNG_COMPOSITE operation from
* happening inside libpng, so this routine sees an 8 or 16-bit gray+alpha
* row and handles the removal or pre-multiplication of the alpha channel.
*/
static int
png_image_read_background(png_voidp argument)
{
png_image_read_control *display = png_voidcast(png_image_read_control*,
argument);
png_imagep image = display->image;
png_structrp png_ptr = image->opaque->png_ptr;
png_inforp info_ptr = image->opaque->info_ptr;
png_uint_32 height = image->height;
png_uint_32 width = image->width;
int pass, passes;
/* Double check the convoluted logic below. We expect to get here with
* libpng doing rgb to gray and gamma correction but background processing
* left to the png_image_read_background function. The rows libpng produce
* might be 8 or 16-bit but should always have two channels; gray plus alpha.
*/
if ((png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
png_error(png_ptr, "lost rgb to gray");
if ((png_ptr->transformations & PNG_COMPOSE) != 0)
png_error(png_ptr, "unexpected compose");
if (png_get_channels(png_ptr, info_ptr) != 2)
png_error(png_ptr, "lost/gained channels");
src/Source/LibPNG/pngread.c view on Meta::CPAN
* PNG.
*/
switch (info_ptr->bit_depth)
{
default:
png_error(png_ptr, "unexpected bit depth");
break;
case 8:
/* 8-bit sRGB gray values with an alpha channel; the alpha channel is
* to be removed by composing on a background: either the row if
* display->background is NULL or display->background->green if not.
* Unlike the code above ALPHA_OPTIMIZED has *not* been done.
*/
{
png_bytep first_row = png_voidcast(png_bytep, display->first_row);
ptrdiff_t step_row = display->row_bytes;
for (pass = 0; pass < passes; ++pass)
{
png_bytep row = png_voidcast(png_bytep,
display->first_row);
src/Source/LibPNG/pngread.c view on Meta::CPAN
stepy = PNG_PASS_ROW_OFFSET(pass);
}
else
{
y = 0;
startx = 0;
stepx = stepy = 1;
}
if (display->background == NULL)
{
for (; y<height; y += stepy)
{
png_bytep inrow = png_voidcast(png_bytep,
display->local_row);
png_bytep outrow = first_row + y * step_row;
png_const_bytep end_row = outrow + width;
/* Read the row, which is packed: */
png_read_row(png_ptr, inrow, NULL);
src/Source/LibPNG/pngread.c view on Meta::CPAN
}
outrow[0] = (png_byte)component;
}
inrow += 2; /* gray and alpha channel */
}
}
}
else /* constant background value */
{
png_byte background8 = display->background->green;
png_uint_16 background = png_sRGB_table[background8];
for (; y<height; y += stepy)
{
png_bytep inrow = png_voidcast(png_bytep,
display->local_row);
png_bytep outrow = first_row + y * step_row;
png_const_bytep end_row = outrow + width;
/* Read the row, which is packed: */
png_read_row(png_ptr, inrow, NULL);
/* Now do the composition on each pixel in this row. */
outrow += startx;
for (; outrow < end_row; outrow += stepx)
{
png_byte alpha = inrow[1];
if (alpha > 0) /* else use background */
{
png_uint_32 component = inrow[0];
if (alpha < 255) /* else just use component */
{
component = png_sRGB_table[component] * alpha;
component += background * (255-alpha);
component = PNG_sRGB_FROM_LINEAR(component);
}
outrow[0] = (png_byte)component;
}
else
outrow[0] = background8;
inrow += 2; /* gray and alpha channel */
}
row += display->row_bytes;
}
}
}
}
break;
src/Source/LibPNG/pngread.c view on Meta::CPAN
{
png_image_read_control *display = png_voidcast(png_image_read_control*,
argument);
png_imagep image = display->image;
png_structrp png_ptr = image->opaque->png_ptr;
png_inforp info_ptr = image->opaque->info_ptr;
png_uint_32 format = image->format;
int linear = (format & PNG_FORMAT_FLAG_LINEAR) != 0;
int do_local_compose = 0;
int do_local_background = 0; /* to avoid double gamma correction bug */
int passes = 0;
/* Add transforms to ensure the correct output format is produced then check
* that the required implementation support is there. Always expand; always
* need 8 bits minimum, no palette and expanded tRNS.
*/
png_set_expand(png_ptr);
/* Now check the format to see if it was modified. */
{
src/Source/LibPNG/pngread.c view on Meta::CPAN
/* Do this first so that we have a record if rgb to gray is happening. */
if ((change & PNG_FORMAT_FLAG_COLOR) != 0)
{
/* gray<->color transformation required. */
if ((format & PNG_FORMAT_FLAG_COLOR) != 0)
png_set_gray_to_rgb(png_ptr);
else
{
/* libpng can't do both rgb to gray and
* background/pre-multiplication if there is also significant gamma
* correction, because both operations require linear colors and
* the code only supports one transform doing the gamma correction.
* Handle this by doing the pre-multiplication or background
* operation in this code, if necessary.
*
* TODO: fix this by rewriting pngrtran.c (!)
*
* For the moment (given that fixing this in pngrtran.c is an
* enormous change) 'do_local_background' is used to indicate that
* the problem exists.
*/
if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
do_local_background = 1/*maybe*/;
png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE,
PNG_RGB_TO_GRAY_DEFAULT, PNG_RGB_TO_GRAY_DEFAULT);
}
change &= ~PNG_FORMAT_FLAG_COLOR;
}
/* Set the gamma appropriately, linear for 16-bit input, sRGB otherwise.
*/
src/Source/LibPNG/pngread.c view on Meta::CPAN
output_gamma = PNG_GAMMA_LINEAR;
}
else
{
mode = PNG_ALPHA_PNG;
output_gamma = PNG_DEFAULT_sRGB;
}
/* If 'do_local_background' is set check for the presence of gamma
* correction; this is part of the work-round for the libpng bug
* described above.
*
* TODO: fix libpng and remove this.
*/
if (do_local_background != 0)
{
png_fixed_point gtest;
/* This is 'png_gamma_threshold' from pngrtran.c; the test used for
* gamma correction, the screen gamma hasn't been set on png_struct
* yet; it's set below. png_struct::gamma, however, is set to the
* final value.
*/
if (png_muldiv(>est, output_gamma, png_ptr->colorspace.gamma,
PNG_FP_1) != 0 && png_gamma_significant(gtest) == 0)
do_local_background = 0;
else if (mode == PNG_ALPHA_STANDARD)
{
do_local_background = 2/*required*/;
mode = PNG_ALPHA_PNG; /* prevent libpng doing it */
}
/* else leave as 1 for the checks below */
}
/* If the bit-depth changes then handle that here. */
if ((change & PNG_FORMAT_FLAG_LINEAR) != 0)
{
if (linear != 0 /*16-bit output*/)
png_set_expand_16(png_ptr);
else /* 8-bit output */
png_set_scale_16(png_ptr);
change &= ~PNG_FORMAT_FLAG_LINEAR;
}
/* Now the background/alpha channel changes. */
if ((change & PNG_FORMAT_FLAG_ALPHA) != 0)
{
/* Removing an alpha channel requires composition for the 8-bit
* formats; for the 16-bit it is already done, above, by the
* pre-multiplication and the channel just needs to be stripped.
*/
if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
{
/* If RGB->gray is happening the alpha channel must be left and the
* operation completed locally.
*
* TODO: fix libpng and remove this.
*/
if (do_local_background != 0)
do_local_background = 2/*required*/;
/* 16-bit output: just remove the channel */
else if (linear != 0) /* compose on black (well, pre-multiply) */
png_set_strip_alpha(png_ptr);
/* 8-bit output: do an appropriate compose */
else if (display->background != NULL)
{
png_color_16 c;
c.index = 0; /*unused*/
c.red = display->background->red;
c.green = display->background->green;
c.blue = display->background->blue;
c.gray = display->background->green;
/* This is always an 8-bit sRGB value, using the 'green' channel
* for gray is much better than calculating the luminance here;
* we can get off-by-one errors in that calculation relative to
* the app expectations and that will show up in transparent
* pixels.
*/
png_set_background_fixed(png_ptr, &c,
PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
0/*gamma: not used*/);
}
else /* compose on row: implemented below. */
{
do_local_compose = 1;
/* This leaves the alpha channel in the output, so it has to be
* removed by the code below. Set the encoding to the 'OPTIMIZE'
* one so the code only has to hack on the pixels that require
src/Source/LibPNG/pngread.c view on Meta::CPAN
# ifdef PNG_FORMAT_AFIRST_SUPPORTED
if ((change & PNG_FORMAT_FLAG_AFIRST) != 0)
{
/* Only relevant if there is an alpha channel - it's particularly
* important to handle this correctly because do_local_compose may
* be set above and then libpng will keep the alpha channel for this
* code to remove.
*/
if ((format & PNG_FORMAT_FLAG_ALPHA) != 0)
{
/* Disable this if doing a local background,
* TODO: remove this when local background is no longer required.
*/
if (do_local_background != 2)
png_set_swap_alpha(png_ptr);
}
else
format &= ~PNG_FORMAT_FLAG_AFIRST;
change &= ~PNG_FORMAT_FLAG_AFIRST;
}
# endif
src/Source/LibPNG/pngread.c view on Meta::CPAN
if (change != 0)
png_error(png_ptr, "png_read_image: unsupported transformation");
}
PNG_SKIP_CHUNKS(png_ptr);
/* Update the 'info' structure and make sure the result is as required; first
* make sure to turn on the interlace handling if it will be required
* (because it can't be turned on *after* the call to png_read_update_info!)
*
* TODO: remove the do_local_background fixup below.
*/
if (do_local_compose == 0 && do_local_background != 2)
passes = png_set_interlace_handling(png_ptr);
png_read_update_info(png_ptr, info_ptr);
{
png_uint_32 info_format = 0;
if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
info_format |= PNG_FORMAT_FLAG_COLOR;
if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
{
/* do_local_compose removes this channel below. */
if (do_local_compose == 0)
{
/* do_local_background does the same if required. */
if (do_local_background != 2 ||
(format & PNG_FORMAT_FLAG_ALPHA) != 0)
info_format |= PNG_FORMAT_FLAG_ALPHA;
}
}
else if (do_local_compose != 0) /* internal error */
png_error(png_ptr, "png_image_read: alpha channel lost");
if (info_ptr->bit_depth == 16)
info_format |= PNG_FORMAT_FLAG_LINEAR;
# ifdef PNG_FORMAT_BGR_SUPPORTED
if ((png_ptr->transformations & PNG_BGR) != 0)
info_format |= PNG_FORMAT_FLAG_BGR;
# endif
# ifdef PNG_FORMAT_AFIRST_SUPPORTED
if (do_local_background == 2)
{
if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
info_format |= PNG_FORMAT_FLAG_AFIRST;
}
if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0 ||
((png_ptr->transformations & PNG_ADD_ALPHA) != 0 &&
(png_ptr->flags & PNG_FLAG_FILLER_AFTER) == 0))
{
if (do_local_background == 2)
png_error(png_ptr, "unexpected alpha swap transformation");
info_format |= PNG_FORMAT_FLAG_AFIRST;
}
# endif
/* This is actually an internal error. */
if (info_format != format)
png_error(png_ptr, "png_read_image: invalid transformations");
}
src/Source/LibPNG/pngread.c view on Meta::CPAN
png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
display->local_row = row;
result = png_safe_execute(image, png_image_read_composite, display);
display->local_row = NULL;
png_free(png_ptr, row);
return result;
}
else if (do_local_background == 2)
{
int result;
png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
display->local_row = row;
result = png_safe_execute(image, png_image_read_background, display);
display->local_row = NULL;
png_free(png_ptr, row);
return result;
}
else
{
png_alloc_size_t row_bytes = display->row_bytes;
src/Source/LibPNG/pngread.c view on Meta::CPAN
png_read_row(png_ptr, row, NULL);
row += row_bytes;
}
}
return 1;
}
}
int PNGAPI
png_image_finish_read(png_imagep image, png_const_colorp background,
void *buffer, png_int_32 row_stride, void *colormap)
{
if (image != NULL && image->version == PNG_IMAGE_VERSION)
{
png_uint_32 check;
if (row_stride == 0)
row_stride = PNG_IMAGE_ROW_STRIDE(*image);
if (row_stride < 0)
src/Source/LibPNG/pngread.c view on Meta::CPAN
(image->colormap_entries > 0 && colormap != NULL))
{
int result;
png_image_read_control display;
memset(&display, 0, (sizeof display));
display.image = image;
display.buffer = buffer;
display.row_stride = row_stride;
display.colormap = colormap;
display.background = background;
display.local_row = NULL;
/* Choose the correct 'end' routine; for the color-map case all the
* setup has already been done.
*/
if ((image->format & PNG_FORMAT_FLAG_COLORMAP) != 0)
result =
png_safe_execute(image, png_image_read_colormap, &display) &&
png_safe_execute(image, png_image_read_colormapped, &display);
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
return 1; /* Ok */
}
}
return 0; /* no png_error possible! */
}
#endif
#ifdef PNG_READ_BACKGROUND_SUPPORTED
/* Handle alpha and tRNS via a background color */
void PNGFAPI
png_set_background_fixed(png_structrp png_ptr,
png_const_color_16p background_color, int background_gamma_code,
int need_expand, png_fixed_point background_gamma)
{
png_debug(1, "in png_set_background_fixed");
if (png_rtran_ok(png_ptr, 0) == 0 || background_color == NULL)
return;
if (background_gamma_code == PNG_BACKGROUND_GAMMA_UNKNOWN)
{
png_warning(png_ptr, "Application must supply a known background gamma");
return;
}
png_ptr->transformations |= PNG_COMPOSE | PNG_STRIP_ALPHA;
png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
png_ptr->background = *background_color;
png_ptr->background_gamma = background_gamma;
png_ptr->background_gamma_type = (png_byte)(background_gamma_code);
if (need_expand != 0)
png_ptr->transformations |= PNG_BACKGROUND_EXPAND;
else
png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
}
# ifdef PNG_FLOATING_POINT_SUPPORTED
void PNGAPI
png_set_background(png_structrp png_ptr,
png_const_color_16p background_color, int background_gamma_code,
int need_expand, double background_gamma)
{
png_set_background_fixed(png_ptr, background_color, background_gamma_code,
need_expand, png_fixed(png_ptr, background_gamma, "png_set_background"));
}
# endif /* FLOATING_POINT */
#endif /* READ_BACKGROUND */
/* Scale 16-bit depth files to 8-bit depth. If both of these are set then the
* one that pngrtran does first (scale) happens. This is necessary to allow the
* TRANSFORM and API behavior to be somewhat consistent, and it's simpler.
*/
#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
void PNGAPI
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
* of:
*
* premultiply the color channels
* do not encode non-opaque pixels
* encode the alpha as well as the color channels
*
* The differences disappear if the input/output ('screen') gamma is 1.0,
* because then the encoding is a no-op and there is only the choice of
* premultiplying the color channels or not.
*
* png_set_alpha_mode and png_set_background interact because both use
* png_compose to do the work. Calling both is only useful when
* png_set_alpha_mode is used to set the default mode - PNG_ALPHA_PNG - along
* with a default gamma value. Otherwise PNG_COMPOSE must not be set.
*/
switch (mode)
{
case PNG_ALPHA_PNG: /* default: png standard */
/* No compose, but it may be set by png_set_background! */
png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
break;
case PNG_ALPHA_ASSOCIATED: /* color channels premultiplied */
compose = 1;
png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
/* The output is linear: */
output_gamma = PNG_FP_1;
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
*/
if (png_ptr->colorspace.gamma == 0)
{
png_ptr->colorspace.gamma = file_gamma;
png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
}
/* But always set the output gamma: */
png_ptr->screen_gamma = output_gamma;
/* Finally, if pre-multiplying, set the background fields to achieve the
* desired result.
*/
if (compose != 0)
{
/* And obtain alpha pre-multiplication by composing on black: */
memset(&png_ptr->background, 0, (sizeof png_ptr->background));
png_ptr->background_gamma = png_ptr->colorspace.gamma; /* just in case */
png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_FILE;
png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
if ((png_ptr->transformations & PNG_COMPOSE) != 0)
png_error(png_ptr,
"conflicting calls to set alpha mode and background");
png_ptr->transformations |= PNG_COMPOSE;
}
}
# ifdef PNG_FLOATING_POINT_SUPPORTED
void PNGAPI
png_set_alpha_mode(png_structrp png_ptr, int mode, double output_gamma)
{
png_set_alpha_mode_fixed(png_ptr, mode, convert_gamma_value(png_ptr,
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
if (png_rtran_ok(png_ptr, 0) == 0)
return;
/* New in libpng-1.5.4 - reserve particular negative values as flags. */
scrn_gamma = translate_gamma_flags(png_ptr, scrn_gamma, 1/*screen*/);
file_gamma = translate_gamma_flags(png_ptr, file_gamma, 0/*file*/);
/* Checking the gamma values for being >0 was added in 1.5.4 along with the
* premultiplied alpha support; this actually hides an undocumented feature
* of the previous implementation which allowed gamma processing to be
* disabled in background handling. There is no evidence (so far) that this
* was being used; however, png_set_background itself accepted and must still
* accept '0' for the gamma value it takes, because it isn't always used.
*
* Since this is an API change (albeit a very minor one that removes an
* undocumented API feature) the following checks were only enabled in
* libpng-1.6.0.
*/
if (file_gamma <= 0)
png_error(png_ptr, "invalid file gamma in png_set_gamma");
if (scrn_gamma <= 0)
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
input_has_transparency = 1;
input_has_alpha = 1;
break;
}
}
}
/* If no alpha we can optimize. */
if (input_has_alpha == 0)
{
/* Any alpha means background and associative alpha processing is
* required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA
* and ENCODE_ALPHA are irrelevant.
*/
png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
if (input_has_transparency == 0)
png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
}
#if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
/* png_set_background handling - deals with the complexity of whether the
* background color is in the file format or the screen format in the case
* where an 'expand' will happen.
*/
/* The following code cannot be entered in the alpha pre-multiplication case
* because PNG_BACKGROUND_EXPAND is cancelled below.
*/
if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0 &&
(png_ptr->transformations & PNG_EXPAND) != 0)
{
{
png_ptr->background.red =
png_ptr->palette[png_ptr->background.index].red;
png_ptr->background.green =
png_ptr->palette[png_ptr->background.index].green;
png_ptr->background.blue =
png_ptr->palette[png_ptr->background.index].blue;
#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
{
if ((png_ptr->transformations & PNG_EXPAND_tRNS) == 0)
{
/* Invert the alpha channel (in tRNS) unless the pixels are
* going to be expanded, in which case leave it for later
*/
int i, istop = png_ptr->num_trans;
for (i=0; i<istop; i++)
png_ptr->trans_alpha[i] = (png_byte)(255 -
png_ptr->trans_alpha[i]);
}
}
#endif /* READ_INVERT_ALPHA */
}
} /* background expand and (therefore) no alpha association. */
#endif /* READ_EXPAND && READ_BACKGROUND */
}
static void /* PRIVATE */
png_init_rgb_transformations(png_structrp png_ptr)
{
/* Added to libpng-1.5.4: check the color type to determine whether there
* is any alpha or transparency in the image and simply cancel the
* background and alpha mode stuff if there isn't.
*/
int input_has_alpha = (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0;
int input_has_transparency = png_ptr->num_trans > 0;
/* If no alpha we can optimize. */
if (input_has_alpha == 0)
{
/* Any alpha means background and associative alpha processing is
* required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA
* and ENCODE_ALPHA are irrelevant.
*/
# ifdef PNG_READ_ALPHA_MODE_SUPPORTED
png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
# endif
if (input_has_transparency == 0)
png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
}
#if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
/* png_set_background handling - deals with the complexity of whether the
* background color is in the file format or the screen format in the case
* where an 'expand' will happen.
*/
/* The following code cannot be entered in the alpha pre-multiplication case
* because PNG_BACKGROUND_EXPAND is cancelled below.
*/
if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0 &&
(png_ptr->transformations & PNG_EXPAND) != 0 &&
(png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
/* i.e., GRAY or GRAY_ALPHA */
{
{
/* Expand background and tRNS chunks */
int gray = png_ptr->background.gray;
int trans_gray = png_ptr->trans_color.gray;
switch (png_ptr->bit_depth)
{
case 1:
gray *= 0xff;
trans_gray *= 0xff;
break;
case 2:
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
default:
case 8:
/* FALL THROUGH (Already 8 bits) */
case 16:
/* Already a full 16 bits */
break;
}
png_ptr->background.red = png_ptr->background.green =
png_ptr->background.blue = (png_uint_16)gray;
if ((png_ptr->transformations & PNG_EXPAND_tRNS) == 0)
{
png_ptr->trans_color.red = png_ptr->trans_color.green =
png_ptr->trans_color.blue = (png_uint_16)trans_gray;
}
}
} /* background expand and (therefore) no alpha association. */
#endif /* READ_EXPAND && READ_BACKGROUND */
}
void /* PRIVATE */
png_init_read_transformations(png_structrp png_ptr)
{
png_debug(1, "in png_init_read_transformations");
/* This internal function is called from png_read_start_row in pngrutil.c
* and it is called before the 'rowbytes' calculation is done, so the code
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
/* The converse - assume the file matches the screen, note that this
* perhaps undesireable default can (from 1.5.4) be changed by calling
* png_set_alpha_mode (even if the alpha handling mode isn't required
* or isn't changed from the default.)
*/
png_ptr->colorspace.gamma = png_reciprocal(png_ptr->screen_gamma);
else /* neither are set */
/* Just in case the following prevents any processing - file and screen
* are both assumed to be linear and there is no way to introduce a
* third gamma value other than png_set_background with 'UNIQUE', and,
* prior to 1.5.4
*/
png_ptr->screen_gamma = png_ptr->colorspace.gamma = PNG_FP_1;
/* We have a gamma value now. */
png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
/* Now turn the gamma transformation on or off as appropriate. Notice
* that PNG_GAMMA just refers to the file->screen correction. Alpha
* composition may independently cause gamma correction because it needs
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
/* Make sure the coefficients for the rgb to gray conversion are set
* appropriately.
*/
if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
png_colorspace_set_rgb_coefficients(png_ptr);
#endif
#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
#if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
/* Detect gray background and attempt to enable optimization for
* gray --> RGB case.
*
* Note: if PNG_BACKGROUND_EXPAND is set and color_type is either RGB or
* RGB_ALPHA (in which case need_expand is superfluous anyway), the
* background color might actually be gray yet not be flagged as such.
* This is not a problem for the current code, which uses
* PNG_BACKGROUND_IS_GRAY only to decide when to do the
* png_do_gray_to_rgb() transformation.
*
* TODO: this code needs to be revised to avoid the complexity and
* interdependencies. The color type of the background should be recorded in
* png_set_background, along with the bit depth, then the code has a record
* of exactly what color space the background is currently in.
*/
if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) != 0)
{
/* PNG_BACKGROUND_EXPAND: the background is in the file color space, so if
* the file was grayscale the background value is gray.
*/
if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0)
png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
}
else if ((png_ptr->transformations & PNG_COMPOSE) != 0)
{
/* PNG_COMPOSE: png_set_background was called with need_expand false,
* so the color is in the color space of the output or png_set_alpha_mode
* was called and the color is black. Ignore RGB_TO_GRAY because that
* happens before GRAY_TO_RGB.
*/
if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
{
if (png_ptr->background.red == png_ptr->background.green &&
png_ptr->background.red == png_ptr->background.blue)
{
png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
png_ptr->background.gray = png_ptr->background.red;
}
}
}
#endif /* READ_EXPAND && READ_BACKGROUND */
#endif /* READ_GRAY_TO_RGB */
/* For indexed PNG data (PNG_COLOR_TYPE_PALETTE) many of the transformations
* can be performed directly on the palette, and some (such as rgb to gray)
* can be optimized inside the palette. This is particularly true of the
* composite (background and alpha) stuff, which can be pretty much all done
* in the palette even if the result is expanded to RGB or gray afterward.
*
* NOTE: this is Not Yet Implemented, the code behaves as in 1.5.1 and
* earlier and the palette stuff is actually handled on the first row. This
* leads to the reported bug that the palette returned by png_get_PLTE is not
* updated.
*/
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
png_init_palette_transformations(png_ptr);
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
png_init_rgb_transformations(png_ptr);
#if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
defined(PNG_READ_EXPAND_16_SUPPORTED)
if ((png_ptr->transformations & PNG_EXPAND_16) != 0 &&
(png_ptr->transformations & PNG_COMPOSE) != 0 &&
(png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 &&
png_ptr->bit_depth != 16)
{
/* TODO: fix this. Because the expand_16 operation is after the compose
* handling the background color must be 8, not 16, bits deep, but the
* application will supply a 16-bit value so reduce it here.
*
* The PNG_BACKGROUND_EXPAND code above does not expand to 16 bits at
* present, so that case is ok (until do_expand_16 is moved.)
*
* NOTE: this discards the low 16 bits of the user supplied background
* color, but until expand_16 works properly there is no choice!
*/
# define CHOP(x) (x)=((png_uint_16)PNG_DIV257(x))
CHOP(png_ptr->background.red);
CHOP(png_ptr->background.green);
CHOP(png_ptr->background.blue);
CHOP(png_ptr->background.gray);
# undef CHOP
}
#endif /* READ_BACKGROUND && READ_EXPAND_16 */
#if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
(defined(PNG_READ_SCALE_16_TO_8_SUPPORTED) || \
defined(PNG_READ_STRIP_16_TO_8_SUPPORTED))
if ((png_ptr->transformations & (PNG_16_TO_8|PNG_SCALE_16_TO_8)) != 0 &&
(png_ptr->transformations & PNG_COMPOSE) != 0 &&
(png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 &&
png_ptr->bit_depth == 16)
{
/* On the other hand, if a 16-bit file is to be reduced to 8-bits per
* component this will also happen after PNG_COMPOSE and so the background
* color must be pre-expanded here.
*
* TODO: fix this too.
*/
png_ptr->background.red = (png_uint_16)(png_ptr->background.red * 257);
png_ptr->background.green =
(png_uint_16)(png_ptr->background.green * 257);
png_ptr->background.blue = (png_uint_16)(png_ptr->background.blue * 257);
png_ptr->background.gray = (png_uint_16)(png_ptr->background.gray * 257);
}
#endif
/* NOTE: below 'PNG_READ_ALPHA_MODE_SUPPORTED' is presumed to also enable the
* background support (see the comments in scripts/pnglibconf.dfa), this
* allows pre-multiplication of the alpha channel to be implemented as
* compositing on black. This is probably sub-optimal and has been done in
* 1.5.4 betas simply to enable external critique and testing (i.e. to
* implement the new API quickly, without lots of internal changes.)
*/
#ifdef PNG_READ_GAMMA_SUPPORTED
# ifdef PNG_READ_BACKGROUND_SUPPORTED
/* Includes ALPHA_MODE */
png_ptr->background_1 = png_ptr->background;
# endif
/* This needs to change - in the palette image case a whole set of tables are
* built when it would be quicker to just calculate the correct value for
* each palette entry directly. Also, the test is too tricky - why check
* PNG_RGB_TO_GRAY if PNG_GAMMA is not set? The answer seems to be that
* PNG_GAMMA is cancelled even if the gamma is known? The test excludes the
* PNG_COMPOSE case, so apparently if there is no *overall* gamma correction
* the gamma tables will not be built even if composition is required on a
* gamma encoded value.
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
* tables.
*/
if ((png_ptr->transformations & PNG_GAMMA) != 0 ||
((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0 &&
(png_gamma_significant(png_ptr->colorspace.gamma) != 0 ||
png_gamma_significant(png_ptr->screen_gamma) != 0)) ||
((png_ptr->transformations & PNG_COMPOSE) != 0 &&
(png_gamma_significant(png_ptr->colorspace.gamma) != 0 ||
png_gamma_significant(png_ptr->screen_gamma) != 0
# ifdef PNG_READ_BACKGROUND_SUPPORTED
|| (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_UNIQUE &&
png_gamma_significant(png_ptr->background_gamma) != 0)
# endif
)) || ((png_ptr->transformations & PNG_ENCODE_ALPHA) != 0 &&
png_gamma_significant(png_ptr->screen_gamma) != 0))
{
png_build_gamma_table(png_ptr, png_ptr->bit_depth);
#ifdef PNG_READ_BACKGROUND_SUPPORTED
if ((png_ptr->transformations & PNG_COMPOSE) != 0)
{
/* Issue a warning about this combination: because RGB_TO_GRAY is
* optimized to do the gamma transform if present yet do_background has
* to do the same thing if both options are set a
* double-gamma-correction happens. This is true in all versions of
* libpng to date.
*/
if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
png_warning(png_ptr,
"libpng does not support gamma+background+rgb_to_gray");
if ((png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) != 0)
{
/* We don't get to here unless there is a tRNS chunk with non-opaque
* entries - see the checking code at the start of this function.
*/
png_color back, back_1;
png_colorp palette = png_ptr->palette;
int num_palette = png_ptr->num_palette;
int i;
if (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_FILE)
{
back.red = png_ptr->gamma_table[png_ptr->background.red];
back.green = png_ptr->gamma_table[png_ptr->background.green];
back.blue = png_ptr->gamma_table[png_ptr->background.blue];
back_1.red = png_ptr->gamma_to_1[png_ptr->background.red];
back_1.green = png_ptr->gamma_to_1[png_ptr->background.green];
back_1.blue = png_ptr->gamma_to_1[png_ptr->background.blue];
}
else
{
png_fixed_point g, gs;
switch (png_ptr->background_gamma_type)
{
case PNG_BACKGROUND_GAMMA_SCREEN:
g = (png_ptr->screen_gamma);
gs = PNG_FP_1;
break;
case PNG_BACKGROUND_GAMMA_FILE:
g = png_reciprocal(png_ptr->colorspace.gamma);
gs = png_reciprocal2(png_ptr->colorspace.gamma,
png_ptr->screen_gamma);
break;
case PNG_BACKGROUND_GAMMA_UNIQUE:
g = png_reciprocal(png_ptr->background_gamma);
gs = png_reciprocal2(png_ptr->background_gamma,
png_ptr->screen_gamma);
break;
default:
g = PNG_FP_1; /* back_1 */
gs = PNG_FP_1; /* back */
break;
}
if (png_gamma_significant(gs) != 0)
{
back.red = png_gamma_8bit_correct(png_ptr->background.red,
gs);
back.green = png_gamma_8bit_correct(png_ptr->background.green,
gs);
back.blue = png_gamma_8bit_correct(png_ptr->background.blue,
gs);
}
else
{
back.red = (png_byte)png_ptr->background.red;
back.green = (png_byte)png_ptr->background.green;
back.blue = (png_byte)png_ptr->background.blue;
}
if (png_gamma_significant(g) != 0)
{
back_1.red = png_gamma_8bit_correct(png_ptr->background.red,
g);
back_1.green = png_gamma_8bit_correct(
png_ptr->background.green, g);
back_1.blue = png_gamma_8bit_correct(png_ptr->background.blue,
g);
}
else
{
back_1.red = (png_byte)png_ptr->background.red;
back_1.green = (png_byte)png_ptr->background.green;
back_1.blue = (png_byte)png_ptr->background.blue;
}
}
for (i = 0; i < num_palette; i++)
{
if (i < (int)png_ptr->num_trans &&
png_ptr->trans_alpha[i] != 0xff)
{
if (png_ptr->trans_alpha[i] == 0)
{
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
/* Prevent the transformations being done again.
*
* NOTE: this is highly dubious; it removes the transformations in
* place. This seems inconsistent with the general treatment of the
* transformations elsewhere.
*/
png_ptr->transformations &= ~(PNG_COMPOSE | PNG_GAMMA);
} /* color_type == PNG_COLOR_TYPE_PALETTE */
/* if (png_ptr->background_gamma_type!=PNG_BACKGROUND_GAMMA_UNKNOWN) */
else /* color_type != PNG_COLOR_TYPE_PALETTE */
{
int gs_sig, g_sig;
png_fixed_point g = PNG_FP_1; /* Correction to linear */
png_fixed_point gs = PNG_FP_1; /* Correction to screen */
switch (png_ptr->background_gamma_type)
{
case PNG_BACKGROUND_GAMMA_SCREEN:
g = png_ptr->screen_gamma;
/* gs = PNG_FP_1; */
break;
case PNG_BACKGROUND_GAMMA_FILE:
g = png_reciprocal(png_ptr->colorspace.gamma);
gs = png_reciprocal2(png_ptr->colorspace.gamma,
png_ptr->screen_gamma);
break;
case PNG_BACKGROUND_GAMMA_UNIQUE:
g = png_reciprocal(png_ptr->background_gamma);
gs = png_reciprocal2(png_ptr->background_gamma,
png_ptr->screen_gamma);
break;
default:
png_error(png_ptr, "invalid background gamma type");
}
g_sig = png_gamma_significant(g);
gs_sig = png_gamma_significant(gs);
if (g_sig != 0)
png_ptr->background_1.gray = png_gamma_correct(png_ptr,
png_ptr->background.gray, g);
if (gs_sig != 0)
png_ptr->background.gray = png_gamma_correct(png_ptr,
png_ptr->background.gray, gs);
if ((png_ptr->background.red != png_ptr->background.green) ||
(png_ptr->background.red != png_ptr->background.blue) ||
(png_ptr->background.red != png_ptr->background.gray))
{
/* RGB or RGBA with color background */
if (g_sig != 0)
{
png_ptr->background_1.red = png_gamma_correct(png_ptr,
png_ptr->background.red, g);
png_ptr->background_1.green = png_gamma_correct(png_ptr,
png_ptr->background.green, g);
png_ptr->background_1.blue = png_gamma_correct(png_ptr,
png_ptr->background.blue, g);
}
if (gs_sig != 0)
{
png_ptr->background.red = png_gamma_correct(png_ptr,
png_ptr->background.red, gs);
png_ptr->background.green = png_gamma_correct(png_ptr,
png_ptr->background.green, gs);
png_ptr->background.blue = png_gamma_correct(png_ptr,
png_ptr->background.blue, gs);
}
}
else
{
/* GRAY, GRAY ALPHA, RGB, or RGBA with gray background */
png_ptr->background_1.red = png_ptr->background_1.green
= png_ptr->background_1.blue = png_ptr->background_1.gray;
png_ptr->background.red = png_ptr->background.green
= png_ptr->background.blue = png_ptr->background.gray;
}
/* The background is now in screen gamma: */
png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_SCREEN;
} /* color_type != PNG_COLOR_TYPE_PALETTE */
}/* png_ptr->transformations & PNG_BACKGROUND */
else
/* Transformation does not include PNG_BACKGROUND */
#endif /* READ_BACKGROUND */
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
/* RGB_TO_GRAY needs to have non-gamma-corrected values! */
&& ((png_ptr->transformations & PNG_EXPAND) == 0 ||
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
#ifdef PNG_READ_BACKGROUND_SUPPORTED
/* No GAMMA transformation (see the hanging else 4 lines above) */
if ((png_ptr->transformations & PNG_COMPOSE) != 0 &&
(png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
{
int i;
int istop = (int)png_ptr->num_trans;
png_color back;
png_colorp palette = png_ptr->palette;
back.red = (png_byte)png_ptr->background.red;
back.green = (png_byte)png_ptr->background.green;
back.blue = (png_byte)png_ptr->background.blue;
for (i = 0; i < istop; i++)
{
if (png_ptr->trans_alpha[i] == 0)
{
palette[i] = back;
}
else if (png_ptr->trans_alpha[i] != 0xff)
{
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
if (info_ptr->bit_depth < 8)
info_ptr->bit_depth = 8;
info_ptr->num_trans = 0;
}
}
#endif
#if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
defined(PNG_READ_ALPHA_MODE_SUPPORTED)
/* The following is almost certainly wrong unless the background value is in
* the screen space!
*/
if ((png_ptr->transformations & PNG_COMPOSE) != 0)
info_ptr->background = png_ptr->background;
#endif
#ifdef PNG_READ_GAMMA_SUPPORTED
/* The following used to be conditional on PNG_GAMMA (prior to 1.5.4),
* however it seems that the code in png_init_read_transformations, which has
* been called before this from png_read_update_info->png_read_start_row
* sometimes does the gamma transform and cancels the flag.
*
* TODO: this looks wrong; the info_ptr should end up with a gamma equal to
* the screen_gamma value. The following probably results in weirdness if
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
row_info->pixel_depth = (png_byte)(row_info->channels *
row_info->bit_depth);
row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
}
return rgb_error;
}
#endif
#if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
defined(PNG_READ_ALPHA_MODE_SUPPORTED)
/* Replace any alpha or transparency with the supplied background color.
* "background" is already in the screen gamma, while "background_1" is
* at a gamma of 1.0. Paletted files have already been taken care of.
*/
static void
png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
{
#ifdef PNG_READ_GAMMA_SUPPORTED
png_const_bytep gamma_table = png_ptr->gamma_table;
png_const_bytep gamma_from_1 = png_ptr->gamma_from_1;
png_const_bytep gamma_to_1 = png_ptr->gamma_to_1;
png_const_uint_16pp gamma_16 = png_ptr->gamma_16_table;
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
case 1:
{
sp = row;
shift = 7;
for (i = 0; i < row_width; i++)
{
if ((png_uint_16)((*sp >> shift) & 0x01)
== png_ptr->trans_color.gray)
{
unsigned int tmp = *sp & (0x7f7f >> (7 - shift));
tmp |= png_ptr->background.gray << shift;
*sp = (png_byte)(tmp & 0xff);
}
if (shift == 0)
{
shift = 7;
sp++;
}
else
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
if (gamma_table != NULL)
{
sp = row;
shift = 6;
for (i = 0; i < row_width; i++)
{
if ((png_uint_16)((*sp >> shift) & 0x03)
== png_ptr->trans_color.gray)
{
unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
tmp |= png_ptr->background.gray << shift;
*sp = (png_byte)(tmp & 0xff);
}
else
{
unsigned int p = (*sp >> shift) & 0x03;
unsigned int g = (gamma_table [p | (p << 2) |
(p << 4) | (p << 6)] >> 6) & 0x03;
unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
tmp |= g << shift;
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
#endif
{
sp = row;
shift = 6;
for (i = 0; i < row_width; i++)
{
if ((png_uint_16)((*sp >> shift) & 0x03)
== png_ptr->trans_color.gray)
{
unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
tmp |= png_ptr->background.gray << shift;
*sp = (png_byte)(tmp & 0xff);
}
if (shift == 0)
{
shift = 6;
sp++;
}
else
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
if (gamma_table != NULL)
{
sp = row;
shift = 4;
for (i = 0; i < row_width; i++)
{
if ((png_uint_16)((*sp >> shift) & 0x0f)
== png_ptr->trans_color.gray)
{
unsigned int tmp = *sp & (0xf0f >> (4 - shift));
tmp |= png_ptr->background.gray << shift;
*sp = (png_byte)(tmp & 0xff);
}
else
{
unsigned int p = (*sp >> shift) & 0x0f;
unsigned int g = (gamma_table[p | (p << 4)] >> 4) &
0x0f;
unsigned int tmp = *sp & (0xf0f >> (4 - shift));
tmp |= g << shift;
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
#endif
{
sp = row;
shift = 4;
for (i = 0; i < row_width; i++)
{
if ((png_uint_16)((*sp >> shift) & 0x0f)
== png_ptr->trans_color.gray)
{
unsigned int tmp = *sp & (0xf0f >> (4 - shift));
tmp |= png_ptr->background.gray << shift;
*sp = (png_byte)(tmp & 0xff);
}
if (shift == 0)
{
shift = 4;
sp++;
}
else
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
case 8:
{
#ifdef PNG_READ_GAMMA_SUPPORTED
if (gamma_table != NULL)
{
sp = row;
for (i = 0; i < row_width; i++, sp++)
{
if (*sp == png_ptr->trans_color.gray)
*sp = (png_byte)png_ptr->background.gray;
else
*sp = gamma_table[*sp];
}
}
else
#endif
{
sp = row;
for (i = 0; i < row_width; i++, sp++)
{
if (*sp == png_ptr->trans_color.gray)
*sp = (png_byte)png_ptr->background.gray;
}
}
break;
}
case 16:
{
#ifdef PNG_READ_GAMMA_SUPPORTED
if (gamma_16 != NULL)
{
sp = row;
for (i = 0; i < row_width; i++, sp += 2)
{
png_uint_16 v;
v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
if (v == png_ptr->trans_color.gray)
{
/* Background is already in screen gamma */
*sp = (png_byte)((png_ptr->background.gray >> 8)
& 0xff);
*(sp + 1) = (png_byte)(png_ptr->background.gray
& 0xff);
}
else
{
v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
*sp = (png_byte)((v >> 8) & 0xff);
*(sp + 1) = (png_byte)(v & 0xff);
}
}
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
{
sp = row;
for (i = 0; i < row_width; i++, sp += 2)
{
png_uint_16 v;
v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
if (v == png_ptr->trans_color.gray)
{
*sp = (png_byte)((png_ptr->background.gray >> 8)
& 0xff);
*(sp + 1) = (png_byte)(png_ptr->background.gray
& 0xff);
}
}
}
break;
}
default:
break;
}
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
#ifdef PNG_READ_GAMMA_SUPPORTED
if (gamma_table != NULL)
{
sp = row;
for (i = 0; i < row_width; i++, sp += 3)
{
if (*sp == png_ptr->trans_color.red &&
*(sp + 1) == png_ptr->trans_color.green &&
*(sp + 2) == png_ptr->trans_color.blue)
{
*sp = (png_byte)png_ptr->background.red;
*(sp + 1) = (png_byte)png_ptr->background.green;
*(sp + 2) = (png_byte)png_ptr->background.blue;
}
else
{
*sp = gamma_table[*sp];
*(sp + 1) = gamma_table[*(sp + 1)];
*(sp + 2) = gamma_table[*(sp + 2)];
}
}
}
else
#endif
{
sp = row;
for (i = 0; i < row_width; i++, sp += 3)
{
if (*sp == png_ptr->trans_color.red &&
*(sp + 1) == png_ptr->trans_color.green &&
*(sp + 2) == png_ptr->trans_color.blue)
{
*sp = (png_byte)png_ptr->background.red;
*(sp + 1) = (png_byte)png_ptr->background.green;
*(sp + 2) = (png_byte)png_ptr->background.blue;
}
}
}
}
else /* if (row_info->bit_depth == 16) */
{
#ifdef PNG_READ_GAMMA_SUPPORTED
if (gamma_16 != NULL)
{
sp = row;
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
+ *(sp + 3));
png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
+ *(sp + 5));
if (r == png_ptr->trans_color.red &&
g == png_ptr->trans_color.green &&
b == png_ptr->trans_color.blue)
{
/* Background is already in screen gamma */
*sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
*(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
*(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
& 0xff);
*(sp + 3) = (png_byte)(png_ptr->background.green
& 0xff);
*(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
& 0xff);
*(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
}
else
{
png_uint_16 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
*sp = (png_byte)((v >> 8) & 0xff);
*(sp + 1) = (png_byte)(v & 0xff);
v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
*(sp + 2) = (png_byte)((v >> 8) & 0xff);
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
+ *(sp + 3));
png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
+ *(sp + 5));
if (r == png_ptr->trans_color.red &&
g == png_ptr->trans_color.green &&
b == png_ptr->trans_color.blue)
{
*sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
*(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
*(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
& 0xff);
*(sp + 3) = (png_byte)(png_ptr->background.green
& 0xff);
*(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
& 0xff);
*(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
}
}
}
}
break;
}
case PNG_COLOR_TYPE_GRAY_ALPHA:
{
if (row_info->bit_depth == 8)
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
for (i = 0; i < row_width; i++, sp += 2)
{
png_uint_16 a = *(sp + 1);
if (a == 0xff)
*sp = gamma_table[*sp];
else if (a == 0)
{
/* Background is already in screen gamma */
*sp = (png_byte)png_ptr->background.gray;
}
else
{
png_byte v, w;
v = gamma_to_1[*sp];
png_composite(w, v, a, png_ptr->background_1.gray);
if (optimize == 0)
w = gamma_from_1[w];
*sp = w;
}
}
}
else
#endif
{
sp = row;
for (i = 0; i < row_width; i++, sp += 2)
{
png_byte a = *(sp + 1);
if (a == 0)
*sp = (png_byte)png_ptr->background.gray;
else if (a < 0xff)
png_composite(*sp, *sp, a, png_ptr->background.gray);
}
}
}
else /* if (png_ptr->bit_depth == 16) */
{
#ifdef PNG_READ_GAMMA_SUPPORTED
if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
gamma_16_to_1 != NULL)
{
sp = row;
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
png_uint_16 v;
v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
*sp = (png_byte)((v >> 8) & 0xff);
*(sp + 1) = (png_byte)(v & 0xff);
}
else if (a == 0)
{
/* Background is already in screen gamma */
*sp = (png_byte)((png_ptr->background.gray >> 8)
& 0xff);
*(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
}
else
{
png_uint_16 g, v, w;
g = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
png_composite_16(v, g, a, png_ptr->background_1.gray);
if (optimize != 0)
w = v;
else
w = gamma_16_from_1[(v&0xff) >> gamma_shift][v >> 8];
*sp = (png_byte)((w >> 8) & 0xff);
*(sp + 1) = (png_byte)(w & 0xff);
}
}
}
else
#endif
{
sp = row;
for (i = 0; i < row_width; i++, sp += 4)
{
png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
+ *(sp + 3));
if (a == 0)
{
*sp = (png_byte)((png_ptr->background.gray >> 8)
& 0xff);
*(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
}
else if (a < 0xffff)
{
png_uint_16 g, v;
g = (png_uint_16)(((*sp) << 8) + *(sp + 1));
png_composite_16(v, g, a, png_ptr->background.gray);
*sp = (png_byte)((v >> 8) & 0xff);
*(sp + 1) = (png_byte)(v & 0xff);
}
}
}
}
break;
}
case PNG_COLOR_TYPE_RGB_ALPHA:
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
if (a == 0xff)
{
*sp = gamma_table[*sp];
*(sp + 1) = gamma_table[*(sp + 1)];
*(sp + 2) = gamma_table[*(sp + 2)];
}
else if (a == 0)
{
/* Background is already in screen gamma */
*sp = (png_byte)png_ptr->background.red;
*(sp + 1) = (png_byte)png_ptr->background.green;
*(sp + 2) = (png_byte)png_ptr->background.blue;
}
else
{
png_byte v, w;
v = gamma_to_1[*sp];
png_composite(w, v, a, png_ptr->background_1.red);
if (optimize == 0) w = gamma_from_1[w];
*sp = w;
v = gamma_to_1[*(sp + 1)];
png_composite(w, v, a, png_ptr->background_1.green);
if (optimize == 0) w = gamma_from_1[w];
*(sp + 1) = w;
v = gamma_to_1[*(sp + 2)];
png_composite(w, v, a, png_ptr->background_1.blue);
if (optimize == 0) w = gamma_from_1[w];
*(sp + 2) = w;
}
}
}
else
#endif
{
sp = row;
for (i = 0; i < row_width; i++, sp += 4)
{
png_byte a = *(sp + 3);
if (a == 0)
{
*sp = (png_byte)png_ptr->background.red;
*(sp + 1) = (png_byte)png_ptr->background.green;
*(sp + 2) = (png_byte)png_ptr->background.blue;
}
else if (a < 0xff)
{
png_composite(*sp, *sp, a, png_ptr->background.red);
png_composite(*(sp + 1), *(sp + 1), a,
png_ptr->background.green);
png_composite(*(sp + 2), *(sp + 2), a,
png_ptr->background.blue);
}
}
}
}
else /* if (row_info->bit_depth == 16) */
{
#ifdef PNG_READ_GAMMA_SUPPORTED
if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
gamma_16_to_1 != NULL)
{
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
*(sp + 3) = (png_byte)(v & 0xff);
v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
*(sp + 4) = (png_byte)((v >> 8) & 0xff);
*(sp + 5) = (png_byte)(v & 0xff);
}
else if (a == 0)
{
/* Background is already in screen gamma */
*sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
*(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
*(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
& 0xff);
*(sp + 3) = (png_byte)(png_ptr->background.green
& 0xff);
*(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
& 0xff);
*(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
}
else
{
png_uint_16 v, w;
v = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
png_composite_16(w, v, a, png_ptr->background_1.red);
if (optimize == 0)
w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >>
8];
*sp = (png_byte)((w >> 8) & 0xff);
*(sp + 1) = (png_byte)(w & 0xff);
v = gamma_16_to_1[*(sp + 3) >> gamma_shift][*(sp + 2)];
png_composite_16(w, v, a, png_ptr->background_1.green);
if (optimize == 0)
w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >>
8];
*(sp + 2) = (png_byte)((w >> 8) & 0xff);
*(sp + 3) = (png_byte)(w & 0xff);
v = gamma_16_to_1[*(sp + 5) >> gamma_shift][*(sp + 4)];
png_composite_16(w, v, a, png_ptr->background_1.blue);
if (optimize == 0)
w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >>
8];
*(sp + 4) = (png_byte)((w >> 8) & 0xff);
*(sp + 5) = (png_byte)(w & 0xff);
}
}
}
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
#endif
{
sp = row;
for (i = 0; i < row_width; i++, sp += 8)
{
png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6))
<< 8) + (png_uint_16)(*(sp + 7)));
if (a == 0)
{
*sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
*(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
*(sp + 2) = (png_byte)((png_ptr->background.green >> 8)
& 0xff);
*(sp + 3) = (png_byte)(png_ptr->background.green
& 0xff);
*(sp + 4) = (png_byte)((png_ptr->background.blue >> 8)
& 0xff);
*(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
}
else if (a < 0xffff)
{
png_uint_16 v;
png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
+ *(sp + 3));
png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
+ *(sp + 5));
png_composite_16(v, r, a, png_ptr->background.red);
*sp = (png_byte)((v >> 8) & 0xff);
*(sp + 1) = (png_byte)(v & 0xff);
png_composite_16(v, g, a, png_ptr->background.green);
*(sp + 2) = (png_byte)((v >> 8) & 0xff);
*(sp + 3) = (png_byte)(v & 0xff);
png_composite_16(v, b, a, png_ptr->background.blue);
*(sp + 4) = (png_byte)((v >> 8) & 0xff);
*(sp + 5) = (png_byte)(v & 0xff);
}
}
}
}
break;
}
default:
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
/* From Andreas Dilger e-mail to png-implement, 26 March 1998:
*
* In most cases, the "simple transparency" should be done prior to doing
* gray-to-RGB, or you will have to test 3x as many bytes to check if a
* pixel is transparent. You would also need to make sure that the
* transparency information is upgraded to RGB.
*
* To summarize, the current flow is:
* - Gray + simple transparency -> compare 1 or 2 gray bytes and composite
* with background "in place" if transparent,
* convert to RGB if necessary
* - Gray + alpha -> composite with gray background and remove alpha bytes,
* convert to RGB if necessary
*
* To support RGB backgrounds for gray images we need:
* - Gray + simple transparency -> convert to RGB + simple transparency,
* compare 3 or 6 bytes and composite with
* background "in place" if transparent
* (3x compare/pixel compared to doing
* composite with gray bkgrnd)
* - Gray + alpha -> convert to RGB + alpha, composite with background and
* remove alpha bytes (3x float
* operations/pixel compared with composite
* on gray background)
*
* Greg's change will do this. The reason it wasn't done before is for
* performance, as this increases the per-pixel operations. If we would check
* in advance if the background was gray or RGB, and position the gray-to-RGB
* transform appropriately, then it would save a lot of work/time.
*/
#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
/* If gray -> RGB, do so now only if background is non-gray; else do later
* for performance reasons
*/
if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0 &&
(png_ptr->mode & PNG_BACKGROUND_IS_GRAY) == 0)
png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
#endif
#if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
defined(PNG_READ_ALPHA_MODE_SUPPORTED)
if ((png_ptr->transformations & PNG_COMPOSE) != 0)
src/Source/LibPNG/pngrutil.c view on Meta::CPAN
&(png_ptr->trans_color));
}
#endif
#ifdef PNG_READ_bKGD_SUPPORTED
void /* PRIVATE */
png_handle_bKGD(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
unsigned int truelen;
png_byte buf[6];
png_color_16 background;
png_debug(1, "in png_handle_bKGD");
if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_chunk_error(png_ptr, "missing IHDR");
else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0 ||
(png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
(png_ptr->mode & PNG_HAVE_PLTE) == 0))
{
src/Source/LibPNG/pngrutil.c view on Meta::CPAN
png_chunk_benign_error(png_ptr, "invalid");
return;
}
png_crc_read(png_ptr, buf, truelen);
if (png_crc_finish(png_ptr, 0) != 0)
return;
/* We convert the index value into RGB components so that we can allow
* arbitrary RGB values for background when we have transparency, and
* so it is easy to determine the RGB values of the background color
* from the info_ptr struct.
*/
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
{
background.index = buf[0];
if (info_ptr != NULL && info_ptr->num_palette != 0)
{
if (buf[0] >= info_ptr->num_palette)
{
png_chunk_benign_error(png_ptr, "invalid index");
return;
}
background.red = (png_uint_16)png_ptr->palette[buf[0]].red;
background.green = (png_uint_16)png_ptr->palette[buf[0]].green;
background.blue = (png_uint_16)png_ptr->palette[buf[0]].blue;
}
else
background.red = background.green = background.blue = 0;
background.gray = 0;
}
else if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0) /* GRAY */
{
background.index = 0;
background.red =
background.green =
background.blue =
background.gray = png_get_uint_16(buf);
}
else
{
background.index = 0;
background.red = png_get_uint_16(buf);
background.green = png_get_uint_16(buf + 2);
background.blue = png_get_uint_16(buf + 4);
background.gray = 0;
}
png_set_bKGD(png_ptr, info_ptr, &background);
}
#endif
#ifdef PNG_READ_hIST_SUPPORTED
void /* PRIVATE */
png_handle_hIST(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
{
unsigned int num, i;
png_uint_16 readbuf[PNG_MAX_PALETTE_LENGTH];
src/Source/LibPNG/pngset.c view on Meta::CPAN
* info struct and allows us to change the structure in the future.
*/
#include "pngpriv.h"
#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
#ifdef PNG_bKGD_SUPPORTED
void PNGAPI
png_set_bKGD(png_const_structrp png_ptr, png_inforp info_ptr,
png_const_color_16p background)
{
png_debug1(1, "in %s storage function", "bKGD");
if (png_ptr == NULL || info_ptr == NULL || background == NULL)
return;
info_ptr->background = *background;
info_ptr->valid |= PNG_INFO_bKGD;
}
#endif
#ifdef PNG_cHRM_SUPPORTED
void PNGFAPI
png_set_cHRM_fixed(png_const_structrp png_ptr, png_inforp info_ptr,
png_fixed_point white_x, png_fixed_point white_y, png_fixed_point red_x,
png_fixed_point red_y, png_fixed_point green_x, png_fixed_point green_y,
png_fixed_point blue_x, png_fixed_point blue_y)
src/Source/LibPNG/pngstruct.h view on Meta::CPAN
png_byte maximum_pixel_depth;
/* pixel depth used for the row buffers */
png_byte transformed_pixel_depth;
/* pixel depth after read/write transforms */
#if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
png_uint_16 filler; /* filler bytes for pixel expansion */
#endif
#if defined(PNG_bKGD_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
defined(PNG_READ_ALPHA_MODE_SUPPORTED)
png_byte background_gamma_type;
png_fixed_point background_gamma;
png_color_16 background; /* background color in screen gamma space */
#ifdef PNG_READ_GAMMA_SUPPORTED
png_color_16 background_1; /* background normalized to gamma 1.0 */
#endif
#endif /* bKGD */
#ifdef PNG_WRITE_FLUSH_SUPPORTED
png_flush_ptr output_flush_fn; /* Function for flushing output */
png_uint_32 flush_dist; /* how many rows apart to flush, 0 - no flush */
png_uint_32 flush_rows; /* number of rows written since last flush */
#endif
#ifdef PNG_READ_GAMMA_SUPPORTED
src/Source/LibPNG/pngtest.c view on Meta::CPAN
#endif
{
png_colorp palette;
int num_palette;
if (png_get_PLTE(read_ptr, read_info_ptr, &palette, &num_palette) != 0)
png_set_PLTE(write_ptr, write_info_ptr, palette, num_palette);
}
#ifdef PNG_bKGD_SUPPORTED
{
png_color_16p background;
if (png_get_bKGD(read_ptr, read_info_ptr, &background) != 0)
{
png_set_bKGD(write_ptr, write_info_ptr, background);
}
}
#endif
#ifdef PNG_hIST_SUPPORTED
{
png_uint_16p hist;
if (png_get_hIST(read_ptr, read_info_ptr, &hist) != 0)
png_set_hIST(write_ptr, write_info_ptr, hist);
}
src/Source/LibPNG/pngwrite.c view on Meta::CPAN
info_ptr->trans_alpha[j] =
(png_byte)(255 - info_ptr->trans_alpha[j]);
}
#endif
png_write_tRNS(png_ptr, info_ptr->trans_alpha, &(info_ptr->trans_color),
info_ptr->num_trans, info_ptr->color_type);
}
#endif
#ifdef PNG_WRITE_bKGD_SUPPORTED
if ((info_ptr->valid & PNG_INFO_bKGD) != 0)
png_write_bKGD(png_ptr, &(info_ptr->background), info_ptr->color_type);
#endif
#ifdef PNG_WRITE_hIST_SUPPORTED
if ((info_ptr->valid & PNG_INFO_hIST) != 0)
png_write_hIST(png_ptr, info_ptr->hist, info_ptr->num_palette);
#endif
#ifdef PNG_WRITE_oFFs_SUPPORTED
if ((info_ptr->valid & PNG_INFO_oFFs) != 0)
png_write_oFFs(png_ptr, info_ptr->x_offset, info_ptr->y_offset,
src/Source/LibPNG/pngwutil.c view on Meta::CPAN
}
else
{
png_app_warning(png_ptr, "Can't write tRNS with an alpha channel");
}
}
#endif
#ifdef PNG_WRITE_bKGD_SUPPORTED
/* Write the background chunk */
void /* PRIVATE */
png_write_bKGD(png_structrp png_ptr, png_const_color_16p back, int color_type)
{
png_byte buf[6];
png_debug(1, "in png_write_bKGD");
if (color_type == PNG_COLOR_TYPE_PALETTE)
{
if (
#ifdef PNG_MNG_FEATURES_SUPPORTED
(png_ptr->num_palette != 0 ||
(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) == 0) &&
#endif
back->index >= png_ptr->num_palette)
{
png_warning(png_ptr, "Invalid background palette index");
return;
}
buf[0] = back->index;
png_write_complete_chunk(png_ptr, png_bKGD, buf, (png_size_t)1);
}
else if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
{
png_save_uint_16(buf, back->red);
src/Source/LibWebP/ChangeLog view on Meta::CPAN
30c8158 add extra assert in Huffman decode code
8967b9f SSE2 for lossless decoding (critical) functions.
699d80e Jump-lookup for Huffman coding
c34307a fix some VS9 warnings about type conversion
eeada35 pngdec: add missing include
54b6510 gif2webp: If aligning to even offsets, extra pixels should be transparent
0bcf5ce Merge "remove a malloc() in case we're using only FILTER_NONE for alpha"
2c07143 remove a malloc() in case we're using only FILTER_NONE for alpha
a4d5f59 Faster lossless decoding
fd53bb7 Merge "alternate LUT-base reverse-bits code"
d1c166e Merge "Container spec: a clarification on background color."
fdb9177 Rename a method
5e96753 Container spec: a clarification on background color.
30e77d0 Merge branch '0.3.0'
1b631e2 alternate LUT-base reverse-bits code
24cc307 ~20% faster lossless decoding
313d853 Speedup for decoding lossless WebP photographs:
24ee098 change the bytes_per_pixels_ field into more evocative use_8b_decode
2a04b03 update ChangeLog (tag: v0.3.1-rc2, tag: v0.3.1)
7288950 Regression fix for alpha channels using color cache:
2e377b5 wicdec: silence a format warning
ad9e42a muxedit: silence some uninitialized warnings
3307c16 Don't set alpha-channel to 0xff for alpha->green uplift
src/Source/LibWebP/ChangeLog view on Meta::CPAN
241cf99 Merge "muxedit: silence some uninitialized warnings"
c8f9c84 Regression fix for alpha unfiltering:
14cd5c6 muxedit: silence some uninitialized warnings
a368db8 dec/vp8l: quiet vs9 x64 type conversion warning
ffae9f3 wicdec: silence a format warning
8cf0701 Alpha encoding: never filter in case of NO_COMPRESSION
825e73b update ChangeLog (tag: v0.3.1-rc1)
abf6f69 update NEWS
5a92c1a bump version to 0.3.1
86daf77 store top Y/U/V samples in packed fashion
67bc353 Revert "add WebPBlendAlpha() function to blend colors against background"
068db59 Intertwined decoding of alpha and RGB
38cc011 Simplify forward-WHT + SSE2 version
3fa595a Support decoding upto given row in DECODE_DATA_FUNC
520f005 DequantizeLevels(): Add 'row' and 'num_rows' args
47374b8 Alpha unfilter for given set of rows
f32097e probe input file and quick-check for WebP format.
a2aed1d configure: improve gl/glut library test
c7e89cb update copyright text
a00380d configure: remove use of AS_VAR_APPEND
a94a88d fix EXIF parsing in PNG
src/Source/LibWebP/ChangeLog view on Meta::CPAN
c7b9218 don't forward declare enums
7a650c6 prevent signed int overflow in left shift ops
31bea32 add precision about dynamic output reallocation with IDecoder
c22877f Add incremental support for extended format files
5051245 Makefile.vc: have 'all' target build everything
8191dec Makefile.vc: flags cleanup
b9d7473 Makefile.vc: drop /FD flag
5568dbc update gitignore
f4c7b65 WebPEncode: An additional check. Start VP8EncLoop/VP8EncTokenLoop only if VP8EncStartAlpha succeeded.
1fb04be pngdec: Avoid a double-free.
dcbb1ca add WebPBlendAlpha() function to blend colors against background
bc9f5fb configure.ac: add AM_PROG_AR for automake >= 1.12
bf867bf Tuned cross_color parameter (step) for lower qual
90e2ec5 Merge "probe input file and quick-check for WebP format."
7180d7f Merge "update copyright text"
830f72b probe input file and quick-check for WebP format.
2ccf58d configure: improve gl/glut library test
d640614 update copyright text
c2113ad Merge "configure: remove use of AS_VAR_APPEND"
9326a56 configure: remove use of AS_VAR_APPEND
ea63d61 fix a type warning on VS9 x86
src/Source/LibWebP/ChangeLog view on Meta::CPAN
a681b4f Rename PRE_VP8 state to WEBP_HEADER
ead4d47 Add incremental support for extended format files
69d0f92 Makefile.vc: have 'all' target build everything
5296749 Makefile.vc: flags cleanup
c61baf0 Makefile.vc: drop /FD flag
3a15125 update gitignore
5167ca4 Merge "WebPEncode: An additional check. Start VP8EncLoop/VP8EncTokenLoop only if VP8EncStartAlpha succeeded."
67708d6 WebPEncode: An additional check. Start VP8EncLoop/VP8EncTokenLoop only if VP8EncStartAlpha succeeded.
b68912a pngdec: Avoid a double-free.
82abbe1 Merge "configure.ac: add AM_PROG_AR for automake >= 1.12"
e7d9548 add WebPBlendAlpha() function to blend colors against background
ed4dc71 configure.ac: add AM_PROG_AR for automake >= 1.12
df4a406 Merge branch '0.3.0'
1e0d4b8 Update ChangeLog (tag: v0.3.0-rc7, tag: v0.3.0)
d52b405 Cosmetic fixes
6cb4a61 misc style fix
68111ab add missing YUVA->ARGB automatic conversion in WebPEncode()
e9a7990 Cosmetic fixes
403bfe8 Container spec: Clarify frame disposal
2aaa423 Merge "add missing YUVA->ARGB automatic conversion in WebPEncode()"
07d87bd add missing YUVA->ARGB automatic conversion in WebPEncode()
142c462 misc style fix
3e7a13a Merge "Container spec: clarify the background color field" into 0.3.0
14af774 container doc: add a note about the 'ANMF' payload
cc635ef Container spec: clarify the background color field
e3e3394 container doc: move RIFF description to own section
4299f39 libwebp/mux: fix double free
33f9a69 Merge "demux: keep a frame tail pointer; used in AddFrame" into 0.3.0
a2a7b95 use WebPDataCopy() instead of re-coding it.
6f18f12 demux: keep a frame tail pointer; used in AddFrame
e5af49e add doc precision about WebPParseHeaders() return codes
db46daa Merge "Makefile.vc: fix dynamic builds" into 0.3.0
53c77af Merge "gif2webp: Bgcolor fix for a special case" into 0.3.0
a5ebd14 gif2webp: Bgcolor fix for a special case
6378f23 Merge "vwebp/animation: fix background dispose" into 0.3.0
3c8eb9a fix bad saturation order in QuantizeBlock
04c7a2e vwebp/animation: fix background dispose
81a5069 Makefile.vc: fix dynamic builds
5f25c39 update ChangeLog (tag: v0.3.0-rc6)
14d42af examples: don't use C99 %zu
5ccf1fe update ChangeLog
2560c24 update NEWS
f43bafc Merge changes Iecccb09c,If5ee9fd2,I3e181ce4 into 0.3.0
a788644 dwebp: warn when decoding animated webp's
302efcd Decode: return more meaningful error for animation
ad45273 WebPBitstreamFeatures: add has_animation field
783dfa4 disable FRGM decoding for good in libwebpmux
src/Source/LibWebP/ChangeLog view on Meta::CPAN
7368b8c Merge "WebPGetFeatures() out of if condition for clarity."
f604c9a Merge "fix windows build"
153f94e fix windows build
847b492 Merge "vwebp: use magenta for 'i'nfo display"
25ea46b Merge "vwebp: add keyboard shortcuts to help output"
bea7cca vwebp: use magenta for 'i'nfo display
8fab161 webpmux: correct -frame param order in help output
03cc23d vwebp: add keyboard shortcuts to help output
068eba8 Demux: Add option to get frame count using GetI()
988b8f5 WebPGetFeatures() out of if condition for clarity.
6933d91 Merge "gif2webp: Be lenient about background color index."
4d0f7c5 Merge "WebPGetFeatures() behavior change:"
fdeeb01 gif2webp: Be lenient about background color index.
ad25032 Merge "multi-threaded alpha encoding for lossy"
4e32d3e Merge "fix compilation of token.c"
f817930 multi-threaded alpha encoding for lossy
8805035 fix compilation of token.c
fc81621 code using the actual values for num_parts_, not the ones from config
7265535 Merge "move the config check from .c to .h"
dd9e76f move the config check from .c to .h
956b217 WebPGetFeatures() behavior change:
df02e4c WebPDemuxGetI behavior change:
633c004 Merge "rebalance method tools (-m) for methods [0..4]"
src/Source/LibWebP/ChangeLog view on Meta::CPAN
6808e69 More spec/code matching in mux:
bd2b46f Merge "doc/webp-container-spec: light cosmetics"
20ead32 doc/webp-container-spec: light cosmetics
1d40a8b configure: add pthread detection
b5e9067 fix some int <-> size_t mix for buffer sizes
e41a759 build: remove libwebpmux from default targets/config
0fc2baa configure: broaden test for libpng-config
45b8272 Merge "restore authorship to lossless bitstream doc"
06ba059 restore authorship to lossless bitstream doc
44a09a3 add missing description of the alpha filtering methods
63db87d Merge "vwebp: add checkboard background for alpha display"
a73b897 vwebp: add checkboard background for alpha display
939158c Merge "vwebp: fix info display"
b35c07d vwebp: fix info display
48b39eb fix underflow for very short bitstreams
7e62298 cosmetics: param alignment, manpage wording
1bd7dd5 Merge changes I7b0afb0d,I7ecc9708
ac69e63 Merge "Updated cwebp man's help for Alpha & Lossless."
c0e8859 Get rid of image_info_ from WebPChunk struct.
135ca69 WebP Container Spec:
eb6f9b8 Updated cwebp man's help for Alpha & Lossless.
0fa844f cosmetic fixes on assert and 'const' where applicable
src/Source/LibWebP/README view on Meta::CPAN
-low_memory ............ reduce memory usage (slower encoding)
-map <int> ............. print map of extra info
-print_psnr ............ prints averaged PSNR distortion
-print_ssim ............ prints averaged SSIM distortion
-print_lsim ............ prints local-similarity distortion
-d <file.pgm> .......... dump the compressed output (PGM file)
-alpha_method <int> .... transparency-compression method (0..1)
-alpha_filter <string> . predictive filtering for alpha plane,
one of: none, fast (default) or best
-alpha_cleanup ......... clean RGB values in transparent area
-blend_alpha <hex> ..... blend colors against background color
expressed as RGB values written in
hexadecimal, e.g. 0xc0e0d0 for red=0xc0
green=0xe0 and blue=0xd0
-noalpha ............... discard any transparency information
-lossless .............. encode image losslessly
-hint <string> ......... specify image characteristics hint,
one of: photo, picture or graph
-metadata <string> ..... comma separated list of metadata to
copy from the input to the output if present.
src/Source/LibWebP/src/demux/demux.demux.c view on Meta::CPAN
}
return 1;
}
// -----------------------------------------------------------------------------
// WebPDemuxer object
static void InitDemux(WebPDemuxer* const dmux, const MemBuffer* const mem) {
dmux->state_ = WEBP_DEMUX_PARSING_HEADER;
dmux->loop_count_ = 1;
dmux->bgcolor_ = 0xFFFFFFFF; // White background by default.
dmux->canvas_width_ = -1;
dmux->canvas_height_ = -1;
dmux->frames_tail_ = &dmux->frames_;
dmux->chunks_tail_ = &dmux->chunks_;
dmux->mem_ = *mem;
}
WebPDemuxer* WebPDemuxInternal(const WebPData* data, int allow_partial,
WebPDemuxState* state, int version) {
const ChunkParser* parser;
( run in 4.261 seconds using v1.01-cache-2.11-cpan-f56aa216473 )