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| author | Niklas Haas <git@haasn.dev> | 2024-12-16 14:49:39 +0100 |
|---|---|---|
| committer | Niklas Haas <git@haasn.dev> | 2024-12-26 20:31:36 +0100 |
| commit | af6d52eec66961f6a502b0f2f390c12226d087cd (patch) | |
| tree | 3c1cc1ddf6d21e3fa8c02be8a8f681356657c2a0 /libswscale/utils.c | |
| parent | 3e6d89cd97d0ec66cc685fec048273e59b3e5958 (diff) | |
| download | ffmpeg-af6d52eec66961f6a502b0f2f390c12226d087cd.tar.gz | |
swscale: use 16-bit intermediate precision for RGB/XYZ conversion
The current logic uses 12-bit linear light math, which is woefully insufficient
and leads to nasty postarization artifacts. This patch simply switches the
internal logic to 16-bit precision.
This raises the memory requirement of these tables from 32 kB to 272 kB.
All relevant FATE tests updated for improved accuracy.
Fixes: #4829
Signed-off-by: Niklas Haas <git@haasn.dev>
Sponsored-by: Sovereign Tech Fund
Diffstat (limited to 'libswscale/utils.c')
| -rw-r--r-- | libswscale/utils.c | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/libswscale/utils.c b/libswscale/utils.c index 80752b7fb0..5235cbed8d 100644 --- a/libswscale/utils.c +++ b/libswscale/utils.c @@ -951,7 +951,8 @@ static void fill_xyztables(SwsInternal *c) {1689, 1464, 739}, { 871, 2929, 296}, { 79, 488, 3891} }; - static int16_t xyzgamma_tab[4096], rgbgamma_tab[4096], xyzgammainv_tab[4096], rgbgammainv_tab[4096]; + static uint16_t xyzgamma_tab[4096], rgbgammainv_tab[4096]; + static uint16_t rgbgamma_tab[65536], xyzgammainv_tab[65536]; memcpy(c->xyz2rgb_matrix, xyz2rgb_matrix, sizeof(c->xyz2rgb_matrix)); memcpy(c->rgb2xyz_matrix, rgb2xyz_matrix, sizeof(c->rgb2xyz_matrix)); @@ -960,15 +961,19 @@ static void fill_xyztables(SwsInternal *c) c->xyzgammainv = xyzgammainv_tab; c->rgbgammainv = rgbgammainv_tab; - if (rgbgamma_tab[4095]) + if (xyzgamma_tab[4095]) return; - /* set gamma vectors */ + /* set input gamma vectors */ for (i = 0; i < 4096; i++) { - xyzgamma_tab[i] = lrint(pow(i / 4095.0, xyzgamma) * 4095.0); - rgbgamma_tab[i] = lrint(pow(i / 4095.0, rgbgamma) * 4095.0); - xyzgammainv_tab[i] = lrint(pow(i / 4095.0, xyzgammainv) * 4095.0); - rgbgammainv_tab[i] = lrint(pow(i / 4095.0, rgbgammainv) * 4095.0); + xyzgamma_tab[i] = lrint(pow(i / 4095.0, xyzgamma) * 65535.0); + rgbgammainv_tab[i] = lrint(pow(i / 4095.0, rgbgammainv) * 65535.0); + } + + /* set output gamma vectors */ + for (i = 0; i < 65536; i++) { + rgbgamma_tab[i] = lrint(pow(i / 65535.0, rgbgamma) * 4095.0); + xyzgammainv_tab[i] = lrint(pow(i / 65535.0, xyzgammainv) * 4095.0); } } |