Alien-FreeImage
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src/Source/LibPNG/pngrtran.c view on Meta::CPAN
case PNG_CRC_NO_CHANGE: /* Leave setting as is */
break;
case PNG_CRC_WARN_USE: /* Warn/use data */
png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE;
break;
case PNG_CRC_QUIET_USE: /* Quiet/use data */
png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE |
PNG_FLAG_CRC_ANCILLARY_NOWARN;
break;
case PNG_CRC_ERROR_QUIT: /* Error/quit */
png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_NOWARN;
break;
case PNG_CRC_WARN_DISCARD: /* Warn/discard data */
case PNG_CRC_DEFAULT:
default:
png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
break;
}
}
#ifdef PNG_READ_TRANSFORMS_SUPPORTED
/* Is it OK to set a transformation now? Only if png_start_read_image or
* png_read_update_info have not been called. It is not necessary for the IHDR
* to have been read in all cases; the need_IHDR parameter allows for this
* check too.
*/
static int
png_rtran_ok(png_structrp png_ptr, int need_IHDR)
{
if (png_ptr != NULL)
{
if ((png_ptr->flags & PNG_FLAG_ROW_INIT) != 0)
png_app_error(png_ptr,
"invalid after png_start_read_image or png_read_update_info");
else if (need_IHDR && (png_ptr->mode & PNG_HAVE_IHDR) == 0)
png_app_error(png_ptr, "invalid before the PNG header has been read");
else
{
/* Turn on failure to initialize correctly for all transforms. */
png_ptr->flags |= PNG_FLAG_DETECT_UNINITIALIZED;
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
png_set_scale_16(png_structrp png_ptr)
{
png_debug(1, "in png_set_scale_16");
if (png_rtran_ok(png_ptr, 0) == 0)
return;
png_ptr->transformations |= PNG_SCALE_16_TO_8;
}
#endif
#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
/* Chop 16-bit depth files to 8-bit depth */
void PNGAPI
png_set_strip_16(png_structrp png_ptr)
{
png_debug(1, "in png_set_strip_16");
if (png_rtran_ok(png_ptr, 0) == 0)
return;
png_ptr->transformations |= PNG_16_TO_8;
}
#endif
#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
void PNGAPI
png_set_strip_alpha(png_structrp png_ptr)
{
png_debug(1, "in png_set_strip_alpha");
if (png_rtran_ok(png_ptr, 0) == 0)
return;
png_ptr->transformations |= PNG_STRIP_ALPHA;
}
#endif
#if defined(PNG_READ_ALPHA_MODE_SUPPORTED) || defined(PNG_READ_GAMMA_SUPPORTED)
static png_fixed_point
translate_gamma_flags(png_structrp png_ptr, png_fixed_point output_gamma,
int is_screen)
{
/* Check for flag values. The main reason for having the old Mac value as a
* flag is that it is pretty near impossible to work out what the correct
* value is from Apple documentation - a working Mac system is needed to
* discover the value!
*/
if (output_gamma == PNG_DEFAULT_sRGB ||
output_gamma == PNG_FP_1 / PNG_DEFAULT_sRGB)
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
* gamma values are passed to the floating point API. This is safe and it
* means the fixed point constants work just fine with the floating point
* API. The alternative would just lead to undetected errors and spurious
* bug reports. Negative values fail inside the _fixed API unless they
* correspond to the flag values.
*/
if (output_gamma > 0 && output_gamma < 128)
output_gamma *= PNG_FP_1;
/* This preserves -1 and -2 exactly: */
output_gamma = floor(output_gamma + .5);
if (output_gamma > PNG_FP_MAX || output_gamma < PNG_FP_MIN)
png_fixed_error(png_ptr, "gamma value");
return (png_fixed_point)output_gamma;
}
# endif
#endif /* READ_ALPHA_MODE || READ_GAMMA */
#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
void PNGFAPI
png_set_alpha_mode_fixed(png_structrp png_ptr, int mode,
png_fixed_point output_gamma)
{
int compose = 0;
png_fixed_point file_gamma;
png_debug(1, "in png_set_alpha_mode");
if (png_rtran_ok(png_ptr, 0) == 0)
return;
output_gamma = translate_gamma_flags(png_ptr, output_gamma, 1/*screen*/);
/* Validate the value to ensure it is in a reasonable range. The value
* is expected to be 1 or greater, but this range test allows for some
* viewing correction values. The intent is to weed out users of this API
* who use the inverse of the gamma value accidentally! Since some of these
* values are reasonable this may have to be changed.
*/
if (output_gamma < 70000 || output_gamma > 300000)
png_error(png_ptr, "output gamma out of expected range");
/* The default file gamma is the inverse of the output gamma; the output
* gamma may be changed below so get the file value first:
*/
file_gamma = png_reciprocal(output_gamma);
/* There are really 8 possibilities here, composed of any combination
* 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;
break;
case PNG_ALPHA_OPTIMIZED: /* associated, non-opaque pixels linear */
compose = 1;
png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
png_ptr->flags |= PNG_FLAG_OPTIMIZE_ALPHA;
/* output_gamma records the encoding of opaque pixels! */
break;
case PNG_ALPHA_BROKEN: /* associated, non-linear, alpha encoded */
compose = 1;
png_ptr->transformations |= PNG_ENCODE_ALPHA;
png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
break;
default:
png_error(png_ptr, "invalid alpha mode");
}
/* Only set the default gamma if the file gamma has not been set (this has
* the side effect that the gamma in a second call to png_set_alpha_mode will
* be ignored.)
*/
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,
output_gamma));
}
# endif
#endif
#ifdef PNG_READ_QUANTIZE_SUPPORTED
/* Dither file to 8-bit. Supply a palette, the current number
* of elements in the palette, the maximum number of elements
* allowed, and a histogram if possible. If the current number
* of colors is greater then the maximum number, the palette will be
* modified to fit in the maximum number. "full_quantize" indicates
* whether we need a quantizing cube set up for RGB images, or if we
* simply are reducing the number of colors in a paletted image.
*/
typedef struct png_dsort_struct
{
struct png_dsort_struct * next;
png_byte left;
png_byte right;
} png_dsort;
typedef png_dsort * png_dsortp;
typedef png_dsort * * png_dsortpp;
void PNGAPI
png_set_quantize(png_structrp png_ptr, png_colorp palette,
int num_palette, int maximum_colors, png_const_uint_16p histogram,
int full_quantize)
{
png_debug(1, "in png_set_quantize");
if (png_rtran_ok(png_ptr, 0) == 0)
return;
png_ptr->transformations |= PNG_QUANTIZE;
if (full_quantize == 0)
{
int i;
png_ptr->quantize_index = (png_bytep)png_malloc(png_ptr,
(png_uint_32)(num_palette * (sizeof (png_byte))));
for (i = 0; i < num_palette; i++)
png_ptr->quantize_index[i] = (png_byte)i;
}
if (num_palette > maximum_colors)
{
if (histogram != NULL)
{
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
int ir, ig, ib;
int r = (palette[i].red >> (8 - PNG_QUANTIZE_RED_BITS));
int g = (palette[i].green >> (8 - PNG_QUANTIZE_GREEN_BITS));
int b = (palette[i].blue >> (8 - PNG_QUANTIZE_BLUE_BITS));
for (ir = 0; ir < num_red; ir++)
{
/* int dr = abs(ir - r); */
int dr = ((ir > r) ? ir - r : r - ir);
int index_r = (ir << (PNG_QUANTIZE_BLUE_BITS +
PNG_QUANTIZE_GREEN_BITS));
for (ig = 0; ig < num_green; ig++)
{
/* int dg = abs(ig - g); */
int dg = ((ig > g) ? ig - g : g - ig);
int dt = dr + dg;
int dm = ((dr > dg) ? dr : dg);
int index_g = index_r | (ig << PNG_QUANTIZE_BLUE_BITS);
for (ib = 0; ib < num_blue; ib++)
{
int d_index = index_g | ib;
/* int db = abs(ib - b); */
int db = ((ib > b) ? ib - b : b - ib);
int dmax = ((dm > db) ? dm : db);
int d = dmax + dt + db;
if (d < (int)distance[d_index])
{
distance[d_index] = (png_byte)d;
png_ptr->palette_lookup[d_index] = (png_byte)i;
}
}
}
}
}
png_free(png_ptr, distance);
}
}
#endif /* READ_QUANTIZE */
#ifdef PNG_READ_GAMMA_SUPPORTED
void PNGFAPI
png_set_gamma_fixed(png_structrp png_ptr, png_fixed_point scrn_gamma,
png_fixed_point file_gamma)
{
png_debug(1, "in png_set_gamma_fixed");
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)
png_error(png_ptr, "invalid screen gamma in png_set_gamma");
/* Set the gamma values unconditionally - this overrides the value in the PNG
* file if a gAMA chunk was present. png_set_alpha_mode provides a
* different, easier, way to default the file gamma.
*/
png_ptr->colorspace.gamma = file_gamma;
png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
png_ptr->screen_gamma = scrn_gamma;
}
# ifdef PNG_FLOATING_POINT_SUPPORTED
void PNGAPI
png_set_gamma(png_structrp png_ptr, double scrn_gamma, double file_gamma)
{
png_set_gamma_fixed(png_ptr, convert_gamma_value(png_ptr, scrn_gamma),
convert_gamma_value(png_ptr, file_gamma));
}
# endif /* FLOATING_POINT */
#endif /* READ_GAMMA */
#ifdef PNG_READ_EXPAND_SUPPORTED
/* Expand paletted images to RGB, expand grayscale images of
* less than 8-bit depth to 8-bit depth, and expand tRNS chunks
* to alpha channels.
*/
void PNGAPI
png_set_expand(png_structrp png_ptr)
{
png_debug(1, "in png_set_expand");
if (png_rtran_ok(png_ptr, 0) == 0)
return;
png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
}
/* GRR 19990627: the following three functions currently are identical
* to png_set_expand(). However, it is entirely reasonable that someone
* might wish to expand an indexed image to RGB but *not* expand a single,
* fully transparent palette entry to a full alpha channel--perhaps instead
* convert tRNS to the grayscale/RGB format (16-bit RGB value), or replace
* the transparent color with a particular RGB value, or drop tRNS entirely.
* IOW, a future version of the library may make the transformations flag
* a bit more fine-grained, with separate bits for each of these three
* functions.
*
* More to the point, these functions make it obvious what libpng will be
* doing, whereas "expand" can (and does) mean any number of things.
*
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
{
/* PNG_GAMMA_THRESHOLD is the threshold for performing gamma
* correction as a difference of the overall transform from 1.0
*
* We want to compare the threshold with s*f - 1, if we get
* overflow here it is because of wacky gamma values so we
* turn on processing anyway.
*/
png_fixed_point gtest;
return !png_muldiv(>est, screen_gamma, file_gamma, PNG_FP_1) ||
png_gamma_significant(gtest);
}
#endif
/* Initialize everything needed for the read. This includes modifying
* the palette.
*/
/* For the moment 'png_init_palette_transformations' and
* 'png_init_rgb_transformations' only do some flag canceling optimizations.
* The intent is that these two routines should have palette or rgb operations
* extracted from 'png_init_read_transformations'.
*/
static void /* PRIVATE */
png_init_palette_transformations(png_structrp png_ptr)
{
/* Called to handle the (input) palette case. In png_do_read_transformations
* the first step is to expand the palette if requested, so this code must
* take care to only make changes that are invariant with respect to the
* palette expansion, or only do them if there is no expansion.
*
* STRIP_ALPHA has already been handled in the caller (by setting num_trans
* to 0.)
*/
int input_has_alpha = 0;
int input_has_transparency = 0;
if (png_ptr->num_trans > 0)
{
int i;
/* Ignore if all the entries are opaque (unlikely!) */
for (i=0; i<png_ptr->num_trans; ++i)
{
if (png_ptr->trans_alpha[i] == 255)
continue;
else if (png_ptr->trans_alpha[i] == 0)
input_has_transparency = 1;
else
{
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:
gray *= 0x55;
trans_gray *= 0x55;
break;
case 4:
gray *= 0x11;
trans_gray *= 0x11;
break;
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
* in here can change or update the transformations flags.
*
* First do updates that do not depend on the details of the PNG image data
* being processed.
*/
#ifdef PNG_READ_GAMMA_SUPPORTED
/* Prior to 1.5.4 these tests were performed from png_set_gamma, 1.5.4 adds
* png_set_alpha_mode and this is another source for a default file gamma so
* the test needs to be performed later - here. In addition prior to 1.5.4
* the tests were repeated for the PALETTE color type here - this is no
* longer necessary (and doesn't seem to have been necessary before.)
*/
{
/* The following temporary indicates if overall gamma correction is
* required.
*/
int gamma_correction = 0;
if (png_ptr->colorspace.gamma != 0) /* has been set */
{
if (png_ptr->screen_gamma != 0) /* screen set too */
gamma_correction = png_gamma_threshold(png_ptr->colorspace.gamma,
png_ptr->screen_gamma);
else
/* Assume the output matches the input; a long time default behavior
* of libpng, although the standard has nothing to say about this.
*/
png_ptr->screen_gamma = png_reciprocal(png_ptr->colorspace.gamma);
}
else if (png_ptr->screen_gamma != 0)
/* 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
* linear data (e.g. if the file has a gAMA chunk but the screen gamma
* hasn't been specified.) In any case this flag may get turned off in
* the code immediately below if the transform can be handled outside the
* row loop.
*/
if (gamma_correction != 0)
png_ptr->transformations |= PNG_GAMMA;
else
png_ptr->transformations &= ~PNG_GAMMA;
}
#endif
/* Certain transformations have the effect of preventing other
* transformations that happen afterward in png_do_read_transformations;
* resolve the interdependencies here. From the code of
* png_do_read_transformations the order is:
*
* 1) PNG_EXPAND (including PNG_EXPAND_tRNS)
* 2) PNG_STRIP_ALPHA (if no compose)
* 3) PNG_RGB_TO_GRAY
* 4) PNG_GRAY_TO_RGB iff !PNG_BACKGROUND_IS_GRAY
* 5) PNG_COMPOSE
* 6) PNG_GAMMA
* 7) PNG_STRIP_ALPHA (if compose)
* 8) PNG_ENCODE_ALPHA
* 9) PNG_SCALE_16_TO_8
* 10) PNG_16_TO_8
* 11) PNG_QUANTIZE (converts to palette)
* 12) PNG_EXPAND_16
* 13) PNG_GRAY_TO_RGB iff PNG_BACKGROUND_IS_GRAY
* 14) PNG_INVERT_MONO
* 15) PNG_INVERT_ALPHA
* 16) PNG_SHIFT
* 17) PNG_PACK
* 18) PNG_BGR
* 19) PNG_PACKSWAP
* 20) PNG_FILLER (includes PNG_ADD_ALPHA)
* 21) PNG_SWAP_ALPHA
* 22) PNG_SWAP_BYTES
* 23) PNG_USER_TRANSFORM [must be last]
*/
#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
(png_ptr->transformations & PNG_COMPOSE) == 0)
{
/* Stripping the alpha channel happens immediately after the 'expand'
* transformations, before all other transformation, so it cancels out
* the alpha handling. It has the side effect negating the effect of
* PNG_EXPAND_tRNS too:
*/
png_ptr->transformations &= ~(PNG_BACKGROUND_EXPAND | PNG_ENCODE_ALPHA |
PNG_EXPAND_tRNS);
png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
/* Kill the tRNS chunk itself too. Prior to 1.5.4 this did not happen
* so transparency information would remain just so long as it wasn't
* expanded. This produces unexpected API changes if the set of things
* that do PNG_EXPAND_tRNS changes (perfectly possible given the
* documentation - which says ask for what you want, accept what you
* get.) This makes the behavior consistent from 1.5.4:
*/
png_ptr->num_trans = 0;
}
#endif /* STRIP_ALPHA supported, no COMPOSE */
#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
/* If the screen gamma is about 1.0 then the OPTIMIZE_ALPHA and ENCODE_ALPHA
* settings will have no effect.
*/
if (png_gamma_significant(png_ptr->screen_gamma) == 0)
{
png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
}
#endif
#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);
else
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.
*
* In 1.5.4 this is addressed below by an additional check on the individual
* file gamma - if it is not 1.0 both RGB_TO_GRAY and COMPOSE need the
* 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)
{
palette[i] = back;
}
else /* if (png_ptr->trans_alpha[i] != 0xff) */
{
png_byte v, w;
v = png_ptr->gamma_to_1[palette[i].red];
png_composite(w, v, png_ptr->trans_alpha[i], back_1.red);
palette[i].red = png_ptr->gamma_from_1[w];
v = png_ptr->gamma_to_1[palette[i].green];
png_composite(w, v, png_ptr->trans_alpha[i], back_1.green);
palette[i].green = png_ptr->gamma_from_1[w];
v = png_ptr->gamma_to_1[palette[i].blue];
png_composite(w, v, png_ptr->trans_alpha[i], back_1.blue);
palette[i].blue = png_ptr->gamma_from_1[w];
}
}
else
{
palette[i].red = png_ptr->gamma_table[palette[i].red];
palette[i].green = png_ptr->gamma_table[palette[i].green];
palette[i].blue = png_ptr->gamma_table[palette[i].blue];
}
}
/* 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 ||
(png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
#endif
)
{
png_colorp palette = png_ptr->palette;
int num_palette = png_ptr->num_palette;
int i;
/* NOTE: there are other transformations that should probably be in
* here too.
*/
for (i = 0; i < num_palette; i++)
{
palette[i].red = png_ptr->gamma_table[palette[i].red];
palette[i].green = png_ptr->gamma_table[palette[i].green];
palette[i].blue = png_ptr->gamma_table[palette[i].blue];
}
/* Done the gamma correction. */
png_ptr->transformations &= ~PNG_GAMMA;
} /* color_type == PALETTE && !PNG_BACKGROUND transformation */
}
#ifdef PNG_READ_BACKGROUND_SUPPORTED
else
#endif
#endif /* READ_GAMMA */
#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)
{
/* The png_composite() macro is defined in png.h */
png_composite(palette[i].red, palette[i].red,
png_ptr->trans_alpha[i], back.red);
png_composite(palette[i].green, palette[i].green,
png_ptr->trans_alpha[i], back.green);
png_composite(palette[i].blue, palette[i].blue,
png_ptr->trans_alpha[i], back.blue);
}
}
png_ptr->transformations &= ~PNG_COMPOSE;
}
#endif /* READ_BACKGROUND */
#ifdef PNG_READ_SHIFT_SUPPORTED
if ((png_ptr->transformations & PNG_SHIFT) != 0 &&
(png_ptr->transformations & PNG_EXPAND) == 0 &&
(png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
{
int i;
int istop = png_ptr->num_palette;
int shift = 8 - png_ptr->sig_bit.red;
png_ptr->transformations &= ~PNG_SHIFT;
/* significant bits can be in the range 1 to 7 for a meaninful result, if
* the number of significant bits is 0 then no shift is done (this is an
* error condition which is silently ignored.)
*/
if (shift > 0 && shift < 8)
for (i=0; i<istop; ++i)
{
int component = png_ptr->palette[i].red;
component >>= shift;
png_ptr->palette[i].red = (png_byte)component;
}
shift = 8 - png_ptr->sig_bit.green;
if (shift > 0 && shift < 8)
for (i=0; i<istop; ++i)
{
int component = png_ptr->palette[i].green;
component >>= shift;
png_ptr->palette[i].green = (png_byte)component;
}
shift = 8 - png_ptr->sig_bit.blue;
if (shift > 0 && shift < 8)
for (i=0; i<istop; ++i)
{
int component = png_ptr->palette[i].blue;
component >>= shift;
png_ptr->palette[i].blue = (png_byte)component;
}
}
#endif /* READ_SHIFT */
}
/* Modify the info structure to reflect the transformations. The
* info should be updated so a PNG file could be written with it,
* assuming the transformations result in valid PNG data.
*/
void /* PRIVATE */
png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr)
{
png_debug(1, "in png_read_transform_info");
#ifdef PNG_READ_EXPAND_SUPPORTED
if ((png_ptr->transformations & PNG_EXPAND) != 0)
{
if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
{
/* This check must match what actually happens in
* png_do_expand_palette; if it ever checks the tRNS chunk to see if
* it is all opaque we must do the same (at present it does not.)
*/
if (png_ptr->num_trans > 0)
info_ptr->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
else
info_ptr->color_type = PNG_COLOR_TYPE_RGB;
info_ptr->bit_depth = 8;
info_ptr->num_trans = 0;
if (png_ptr->palette == NULL)
png_error (png_ptr, "Palette is NULL in indexed image");
}
else
{
if (png_ptr->num_trans != 0)
{
if ((png_ptr->transformations & PNG_EXPAND_tRNS) != 0)
info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
}
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
* the info_ptr is used by the app after the rows have been read.
*/
info_ptr->colorspace.gamma = png_ptr->colorspace.gamma;
#endif
if (info_ptr->bit_depth == 16)
{
# ifdef PNG_READ_16BIT_SUPPORTED
# ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
if ((png_ptr->transformations & PNG_SCALE_16_TO_8) != 0)
info_ptr->bit_depth = 8;
# endif
# ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
if ((png_ptr->transformations & PNG_16_TO_8) != 0)
info_ptr->bit_depth = 8;
# endif
# else
/* No 16 bit support: force chopping 16-bit input down to 8, in this case
* the app program can chose if both APIs are available by setting the
* correct scaling to use.
*/
# ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
/* For compatibility with previous versions use the strip method by
* default. This code works because if PNG_SCALE_16_TO_8 is already
* set the code below will do that in preference to the chop.
*/
png_ptr->transformations |= PNG_16_TO_8;
info_ptr->bit_depth = 8;
# else
# ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
png_ptr->transformations |= PNG_SCALE_16_TO_8;
info_ptr->bit_depth = 8;
# else
CONFIGURATION ERROR: you must enable at least one 16 to 8 method
# endif
# endif
#endif /* !READ_16BIT */
}
#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0)
info_ptr->color_type = (png_byte)(info_ptr->color_type |
PNG_COLOR_MASK_COLOR);
#endif
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
*(dp++) = (png_byte)((w>>8) & 0xff);
*(dp++) = (png_byte)(w & 0xff);
if (have_alpha != 0)
{
*(dp++) = *(sp++);
*(dp++) = *(sp++);
}
}
}
else
#endif
{
png_bytep sp = row;
png_bytep dp = row;
png_uint_32 i;
for (i = 0; i < row_width; i++)
{
png_uint_16 red, green, blue, gray16;
red = (png_uint_16)(((*(sp)) << 8) | *(sp + 1)); sp += 2;
green = (png_uint_16)(((*(sp)) << 8) | *(sp + 1)); sp += 2;
blue = (png_uint_16)(((*(sp)) << 8) | *(sp + 1)); sp += 2;
if (red != green || red != blue)
rgb_error |= 1;
/* From 1.5.5 in the 16 bit case do the accurate conversion even
* in the 'fast' case - this is because this is where the code
* ends up when handling linear 16 bit data.
*/
gray16 = (png_uint_16)((rc*red + gc*green + bc*blue + 16384) >>
15);
*(dp++) = (png_byte)((gray16 >> 8) & 0xff);
*(dp++) = (png_byte)(gray16 & 0xff);
if (have_alpha != 0)
{
*(dp++) = *(sp++);
*(dp++) = *(sp++);
}
}
}
}
row_info->channels = (png_byte)(row_info->channels - 2);
row_info->color_type = (png_byte)(row_info->color_type &
~PNG_COLOR_MASK_COLOR);
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;
png_const_uint_16pp gamma_16_from_1 = png_ptr->gamma_16_from_1;
png_const_uint_16pp gamma_16_to_1 = png_ptr->gamma_16_to_1;
int gamma_shift = png_ptr->gamma_shift;
int optimize = (png_ptr->flags & PNG_FLAG_OPTIMIZE_ALPHA) != 0;
#endif
png_bytep sp;
png_uint_32 i;
png_uint_32 row_width = row_info->width;
int shift;
png_debug(1, "in png_do_compose");
{
switch (row_info->color_type)
{
case PNG_COLOR_TYPE_GRAY:
{
switch (row_info->bit_depth)
{
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
shift--;
}
break;
}
case 2:
{
#ifdef PNG_READ_GAMMA_SUPPORTED
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;
*sp = (png_byte)(tmp & 0xff);
}
if (shift == 0)
{
shift = 6;
sp++;
}
else
shift -= 2;
}
}
else
#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
shift -= 2;
}
}
break;
}
case 4:
{
#ifdef PNG_READ_GAMMA_SUPPORTED
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;
*sp = (png_byte)(tmp & 0xff);
}
if (shift == 0)
{
shift = 4;
sp++;
}
else
shift -= 4;
}
}
else
#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
shift -= 4;
}
}
break;
}
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);
}
}
}
else
#endif
{
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;
}
break;
}
case PNG_COLOR_TYPE_RGB:
{
if (row_info->bit_depth == 8)
{
#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;
for (i = 0; i < row_width; i++, sp += 6)
{
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));
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);
*(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
#endif
{
sp = row;
for (i = 0; i < row_width; i++, sp += 6)
{
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));
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)
{
#ifdef PNG_READ_GAMMA_SUPPORTED
if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
gamma_table != NULL)
{
sp = row;
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;
for (i = 0; i < row_width; i++, sp += 4)
{
png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
+ *(sp + 3));
if (a == (png_uint_16)0xffff)
{
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:
{
if (row_info->bit_depth == 8)
{
#ifdef PNG_READ_GAMMA_SUPPORTED
if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
gamma_table != NULL)
{
sp = row;
for (i = 0; i < row_width; i++, sp += 4)
{
png_byte a = *(sp + 3);
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)
{
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 == (png_uint_16)0xffff)
{
png_uint_16 v;
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);
*(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);
}
}
}
else
#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:
break;
}
}
}
#endif /* READ_BACKGROUND || READ_ALPHA_MODE */
#ifdef PNG_READ_GAMMA_SUPPORTED
/* Gamma correct the image, avoiding the alpha channel. Make sure
* you do this after you deal with the transparency issue on grayscale
* or RGB images. If your bit depth is 8, use gamma_table, if it
* is 16, use gamma_16_table and gamma_shift. Build these with
* build_gamma_table().
*/
static void
png_do_gamma(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
{
png_const_bytep gamma_table = png_ptr->gamma_table;
png_const_uint_16pp gamma_16_table = png_ptr->gamma_16_table;
int gamma_shift = png_ptr->gamma_shift;
png_bytep sp;
png_uint_32 i;
png_uint_32 row_width=row_info->width;
png_debug(1, "in png_do_gamma");
if (((row_info->bit_depth <= 8 && gamma_table != NULL) ||
(row_info->bit_depth == 16 && gamma_16_table != NULL)))
{
switch (row_info->color_type)
{
case PNG_COLOR_TYPE_RGB:
{
if (row_info->bit_depth == 8)
{
sp = row;
for (i = 0; i < row_width; i++)
{
*sp = gamma_table[*sp];
sp++;
*sp = gamma_table[*sp];
sp++;
*sp = gamma_table[*sp];
sp++;
}
}
else /* if (row_info->bit_depth == 16) */
{
sp = row;
src/Source/LibPNG/pngrtran.c view on Meta::CPAN
{
if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
{
png_do_expand_palette(row_info, png_ptr->row_buf + 1,
png_ptr->palette, png_ptr->trans_alpha, png_ptr->num_trans);
}
else
{
if (png_ptr->num_trans != 0 &&
(png_ptr->transformations & PNG_EXPAND_tRNS) != 0)
png_do_expand(row_info, png_ptr->row_buf + 1,
&(png_ptr->trans_color));
else
png_do_expand(row_info, png_ptr->row_buf + 1,
NULL);
}
}
#endif
#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
(png_ptr->transformations & PNG_COMPOSE) == 0 &&
(row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
png_do_strip_channel(row_info, png_ptr->row_buf + 1,
0 /* at_start == false, because SWAP_ALPHA happens later */);
#endif
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0)
{
int rgb_error =
png_do_rgb_to_gray(png_ptr, row_info,
png_ptr->row_buf + 1);
if (rgb_error != 0)
{
png_ptr->rgb_to_gray_status=1;
if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
PNG_RGB_TO_GRAY_WARN)
png_warning(png_ptr, "png_do_rgb_to_gray found nongray pixel");
if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
PNG_RGB_TO_GRAY_ERR)
png_error(png_ptr, "png_do_rgb_to_gray found nongray pixel");
}
}
#endif
/* 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)
png_do_compose(row_info, png_ptr->row_buf + 1, png_ptr);
#endif
#ifdef PNG_READ_GAMMA_SUPPORTED
if ((png_ptr->transformations & PNG_GAMMA) != 0 &&
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
/* Because RGB_TO_GRAY does the gamma transform. */
(png_ptr->transformations & PNG_RGB_TO_GRAY) == 0 &&
#endif
#if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
defined(PNG_READ_ALPHA_MODE_SUPPORTED)
/* Because PNG_COMPOSE does the gamma transform if there is something to
* do (if there is an alpha channel or transparency.)
*/
!((png_ptr->transformations & PNG_COMPOSE) &&
((png_ptr->num_trans != 0) ||
(png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)) &&
#endif
/* Because png_init_read_transformations transforms the palette, unless
* RGB_TO_GRAY will do the transform.
*/
(png_ptr->color_type != PNG_COLOR_TYPE_PALETTE))
png_do_gamma(row_info, png_ptr->row_buf + 1, png_ptr);
#endif
#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 &&
(png_ptr->transformations & PNG_COMPOSE) != 0 &&
(row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
png_do_strip_channel(row_info, png_ptr->row_buf + 1,
0 /* at_start == false, because SWAP_ALPHA happens later */);
#endif
#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
if ((png_ptr->transformations & PNG_ENCODE_ALPHA) != 0 &&
(row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0)
png_do_encode_alpha(row_info, png_ptr->row_buf + 1, png_ptr);
#endif
#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
if ((png_ptr->transformations & PNG_SCALE_16_TO_8) != 0)
png_do_scale_16_to_8(row_info, png_ptr->row_buf + 1);
#endif
#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
/* There is no harm in doing both of these because only one has any effect,
* by putting the 'scale' option first if the app asks for scale (either by
* calling the API or in a TRANSFORM flag) this is what happens.
*/
( run in 1.820 second using v1.01-cache-2.11-cpan-0d23b851a93 )