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src/Source/LibJPEG/jccolor.c  view on Meta::CPAN

      /* Y */
      outptr0[col] = (JSAMPLE)
		((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF])
		 >> SCALEBITS);
      /* Cb */
      outptr1[col] = (JSAMPLE)
		((ctab[r+R_CB_OFF] + ctab[g+G_CB_OFF] + ctab[b+B_CB_OFF])
		 >> SCALEBITS);
      /* Cr */
      outptr2[col] = (JSAMPLE)
		((ctab[r+R_CR_OFF] + ctab[g+G_CR_OFF] + ctab[b+B_CR_OFF])
		 >> SCALEBITS);
      inptr += RGB_PIXELSIZE;
    }
  }
}


/**************** Cases other than RGB -> YCbCr **************/


/*
 * Convert some rows of samples to the JPEG colorspace.
 * This version handles RGB->grayscale conversion, which is the same
 * as the RGB->Y portion of RGB->YCbCr.
 * We assume rgb_ycc_start has been called (we only use the Y tables).
 */

METHODDEF(void)
rgb_gray_convert (j_compress_ptr cinfo,
		  JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
		  JDIMENSION output_row, int num_rows)
{
  my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
  register INT32 * ctab = cconvert->rgb_ycc_tab;
  register int r, g, b;
  register JSAMPROW inptr;
  register JSAMPROW outptr;
  register JDIMENSION col;
  JDIMENSION num_cols = cinfo->image_width;

  while (--num_rows >= 0) {
    inptr = *input_buf++;
    outptr = output_buf[0][output_row++];
    for (col = 0; col < num_cols; col++) {
      r = GETJSAMPLE(inptr[RGB_RED]);
      g = GETJSAMPLE(inptr[RGB_GREEN]);
      b = GETJSAMPLE(inptr[RGB_BLUE]);
      /* Y */
      outptr[col] = (JSAMPLE)
		((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF])
		 >> SCALEBITS);
      inptr += RGB_PIXELSIZE;
    }
  }
}


/*
 * Convert some rows of samples to the JPEG colorspace.
 * This version handles Adobe-style CMYK->YCCK conversion,
 * where we convert R=1-C, G=1-M, and B=1-Y to YCbCr using the same
 * conversion as above, while passing K (black) unchanged.
 * We assume rgb_ycc_start has been called.
 */

METHODDEF(void)
cmyk_ycck_convert (j_compress_ptr cinfo,
		   JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
		   JDIMENSION output_row, int num_rows)
{
  my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
  register INT32 * ctab = cconvert->rgb_ycc_tab;
  register int r, g, b;
  register JSAMPROW inptr;
  register JSAMPROW outptr0, outptr1, outptr2, outptr3;
  register JDIMENSION col;
  JDIMENSION num_cols = cinfo->image_width;

  while (--num_rows >= 0) {
    inptr = *input_buf++;
    outptr0 = output_buf[0][output_row];
    outptr1 = output_buf[1][output_row];
    outptr2 = output_buf[2][output_row];
    outptr3 = output_buf[3][output_row];
    output_row++;
    for (col = 0; col < num_cols; col++) {
      r = MAXJSAMPLE - GETJSAMPLE(inptr[0]);
      g = MAXJSAMPLE - GETJSAMPLE(inptr[1]);
      b = MAXJSAMPLE - GETJSAMPLE(inptr[2]);
      /* K passes through as-is */
      outptr3[col] = inptr[3];	/* don't need GETJSAMPLE here */
      /* If the inputs are 0..MAXJSAMPLE, the outputs of these equations
       * must be too; we do not need an explicit range-limiting operation.
       * Hence the value being shifted is never negative, and we don't
       * need the general RIGHT_SHIFT macro.
       */
      /* Y */
      outptr0[col] = (JSAMPLE)
		((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF])
		 >> SCALEBITS);
      /* Cb */
      outptr1[col] = (JSAMPLE)
		((ctab[r+R_CB_OFF] + ctab[g+G_CB_OFF] + ctab[b+B_CB_OFF])
		 >> SCALEBITS);
      /* Cr */
      outptr2[col] = (JSAMPLE)
		((ctab[r+R_CR_OFF] + ctab[g+G_CR_OFF] + ctab[b+B_CR_OFF])
		 >> SCALEBITS);
      inptr += 4;
    }
  }
}


/*
 * Convert some rows of samples to the JPEG colorspace.
 * [R,G,B] to [R-G,G,B-G] conversion with modulo calculation
 * (forward reversible color transform).
 * This can be seen as an adaption of the general RGB->YCbCr
 * conversion equation with Kr = Kb = 0, while replacing the