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Merge branch 'ijg.lossless' into dev

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Lossless: Accommodate LJT colorspace/SIMD exts

In libjpeg-turbo, grayscale_convert() and null_convert() aren't the only
lossless color conversion algorithms.  We can also losslessly convert
RGB to and from any of the extended RGB colorspaces, and some platforms
have SIMD-accelerated null color conversion.

This commit also disallows RGB565 output in lossless mode, and it moves
the IsExtRGB() macro from cdjpeg.h to jpegint.h and repurposes it to
make jinit_color_converter() and jinit_color_deconverter() more
readable.
This commit is contained in:
DRC
2022-11-16 12:18:45 -06:00
parent 918ace631e af618ffe09
commit 3fb10c35d8
7 changed files with 44 additions and 63 deletions
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21
jdcolor.c
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@@ -776,10 +776,15 @@ _jinit_color_deconverter(j_decompress_ptr cinfo)
/* Set out_color_components and conversion method based on requested space.
* Also clear the component_needed flags for any unused components,
* so that earlier pipeline stages can avoid useless computation.
* NOTE: We do not allow any lossy color conversion algorithms in lossless
* mode.
*/
switch (cinfo->out_color_space) {
case JCS_GRAYSCALE:
if (cinfo->master->lossless &&
cinfo->jpeg_color_space != cinfo->out_color_space)
ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
cinfo->out_color_components = 1;
if (cinfo->jpeg_color_space == JCS_GRAYSCALE ||
cinfo->jpeg_color_space == JCS_YCbCr) {
@@ -805,6 +810,8 @@ _jinit_color_deconverter(j_decompress_ptr cinfo)
case JCS_EXT_BGRA:
case JCS_EXT_ABGR:
case JCS_EXT_ARGB:
if (cinfo->master->lossless && cinfo->jpeg_color_space != JCS_RGB)
ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
cinfo->out_color_components = rgb_pixelsize[cinfo->out_color_space];
if (cinfo->jpeg_color_space == JCS_YCbCr) {
#ifdef WITH_SIMD
@@ -831,6 +838,8 @@ _jinit_color_deconverter(j_decompress_ptr cinfo)
break;
case JCS_RGB565:
if (cinfo->master->lossless)
ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
cinfo->out_color_components = 3;
if (cinfo->dither_mode == JDITHER_NONE) {
if (cinfo->jpeg_color_space == JCS_YCbCr) {
@@ -864,6 +873,9 @@ _jinit_color_deconverter(j_decompress_ptr cinfo)
break;
case JCS_CMYK:
if (cinfo->master->lossless &&
cinfo->jpeg_color_space != cinfo->out_color_space)
ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
cinfo->out_color_components = 4;
if (cinfo->jpeg_color_space == JCS_YCCK) {
cconvert->pub._color_convert = ycck_cmyk_convert;
@@ -884,15 +896,6 @@ _jinit_color_deconverter(j_decompress_ptr cinfo)
break;
}
/* Prevent lossy color conversion in lossless mode */
if (cinfo->master->lossless) {
if ((cinfo->out_color_space == JCS_GRAYSCALE &&
cinfo->jpeg_color_space != JCS_GRAYSCALE) ||
(cinfo->out_color_space != JCS_GRAYSCALE &&
cconvert->pub._color_convert != null_convert))
ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
}
if (cinfo->quantize_colors)
cinfo->output_components = 1; /* single colormapped output component */
else