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Make use of gAMA and sRGB PNG chunks 

Neither EoG nor gThumb handle this correctly.
This commit is contained in:
Přemysl Eric Janouch 2021-12-26 03:10:50 +01:00
parent e5b1a1861c
commit 2f993502fc
Signed by: p
GPG Key ID: A0420B94F92B9493
1 changed files with 45 additions and 4 deletions
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49
fiv-io.c
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@ -198,6 +198,30 @@ fiv_io_profile_new_sRGB(void)
#endif
}
FivIoProfile
fiv_io_profile_new_sRGB_gamma(double gamma)
{
#ifdef HAVE_LCMS2
// TODO(p): Make sure to use the library in a thread-safe manner.
cmsContext context = NULL;
static const cmsCIExyY D65 = {0.3127, 0.3290, 1.0};
static const cmsCIExyYTRIPLE primaries = {
{0.6400, 0.3300, 1.0}, {0.3000, 0.6000, 1.0}, {0.1500, 0.0600, 1.0}};
cmsToneCurve *curve = cmsBuildGamma(context, gamma);
if (!curve)
return NULL;
cmsHPROFILE profile = cmsCreateRGBProfileTHR(
context, &D65, &primaries, (cmsToneCurve *[3]){curve, curve, curve});
cmsFreeToneCurve(curve);
return profile;
#else
(void) gamma;
return NULL;
#endif
}
static FivIoProfile
fiv_io_profile_new_from_bytes(GBytes *bytes)
{
@ -740,13 +764,17 @@ open_wuffs(wuffs_base__image_decoder *dec, wuffs_base__io_buffer src,
struct load_wuffs_frame_context ctx = {
.dec = dec, .src = &src, .target = profile};
// TODO(p): PNG also has sRGB and gAMA, as well as text chunks (Wuffs #58).
// The former two use WUFFS_BASE__MORE_INFORMATION__FLAVOR__METADATA_PARSED.
// TODO(p): PNG text chunks (Wuffs #58).
wuffs_base__image_decoder__set_report_metadata(
ctx.dec, WUFFS_BASE__FOURCC__EXIF, true);
wuffs_base__image_decoder__set_report_metadata(
ctx.dec, WUFFS_BASE__FOURCC__ICCP, true);
wuffs_base__image_decoder__set_report_metadata(
ctx.dec, WUFFS_BASE__FOURCC__SRGB, true);
wuffs_base__image_decoder__set_report_metadata(
ctx.dec, WUFFS_BASE__FOURCC__GAMA, true);
double gamma = 0;
while (true) {
wuffs_base__status status =
wuffs_base__image_decoder__decode_image_config(
@ -786,6 +814,14 @@ open_wuffs(wuffs_base__image_decoder *dec, wuffs_base__io_buffer src,
}
ctx.meta_xmp = bytes;
continue;
case WUFFS_BASE__FOURCC__SRGB:
gamma = 2.2;
break;
case WUFFS_BASE__FOURCC__GAMA:
gamma = 1e5 /
wuffs_base__more_information__metadata_parsed__gama(&minfo);
break;
}
g_bytes_unref(bytes);
@ -805,8 +841,13 @@ open_wuffs(wuffs_base__image_decoder *dec, wuffs_base__io_buffer src,
goto fail;
}
if (ctx.target && ctx.meta_iccp)
ctx.source = fiv_io_profile_new_from_bytes(ctx.meta_iccp);
// TODO(p): Improve our simplistic PNG handling of: gAMA, cHRM, sRGB.
if (ctx.target) {
if (ctx.meta_iccp)
ctx.source = fiv_io_profile_new_from_bytes(ctx.meta_iccp);
else if (isfinite(gamma) && gamma > 0)
ctx.source = fiv_io_profile_new_sRGB_gamma(gamma);
}
// Wuffs maps tRNS to BGRA in `decoder.decode_trns?`, we should be fine.
// wuffs_base__pixel_format__transparency() doesn't reflect the image file.