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JPEG: handle CMYK/YCCK images

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No real colourspace conversion here, so expect oversaturated images

Fixes #2570.
This commit is contained in:
John-Mark Bell 2018-01-20 17:57:52 +00:00
parent 17ae38771d
commit fe45bc1dbe
1 changed files with 40 additions and 15 deletions
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29
content/handlers/image/jpeg.c
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@ -214,7 +214,12 @@ jpeg_cache_convert(struct content *c)
jpeg_read_header(&cinfo, TRUE);
/* set output processing parameters */
if (cinfo.jpeg_color_space == JCS_CMYK ||
cinfo.jpeg_color_space == JCS_YCCK) {
cinfo.out_color_space = JCS_CMYK;
} else {
cinfo.out_color_space = JCS_RGB;
}
cinfo.dct_method = JDCT_ISLOW;
/* commence the decompression, output parameters now valid */
@ -248,8 +253,28 @@ jpeg_cache_convert(struct content *c)
rowstride * cinfo.output_scanline);
jpeg_read_scanlines(&cinfo, scanlines, 1);
if (cinfo.out_color_space == JCS_CMYK) {
int i;
for (i = width - 1; 0 <= i; i--) {
/* Trivial inverse CMYK -> RGBA */
const int c = scanlines[0][i * 4 + 0];
const int m = scanlines[0][i * 4 + 1];
const int y = scanlines[0][i * 4 + 2];
const int k = scanlines[0][i * 4 + 3];
const int ck = c * k;
const int mk = m * k;
const int yk = y * k;
#define DIV255(x) ((x) + 1 + ((x) >> 8)) >> 8
scanlines[0][i * 4 + 0] = DIV255(ck);
scanlines[0][i * 4 + 1] = DIV255(mk);
scanlines[0][i * 4 + 2] = DIV255(yk);
scanlines[0][i * 4 + 3] = 0xff;
#undef DIV255
}
} else {
#if RGB_RED != 0 || RGB_GREEN != 1 || RGB_BLUE != 2 || RGB_PIXELSIZE != 4
{
/* Missmatch between configured libjpeg pixel format and
* NetSurf pixel format. Convert to RGBA */
int i;
@ -262,8 +287,8 @@ jpeg_cache_convert(struct content *c)
scanlines[0][i * 4 + 2] = b;
scanlines[0][i * 4 + 3] = 0xff;
}
}
#endif
}
} while (cinfo.output_scanline != cinfo.output_height);
guit->bitmap->modified(bitmap);