Re: [FFmpeg-devel] [PATCH] avcodec/exr: tag gamma=1.0 output as linear light
tor 2023-08-17 klockan 14:04 -0400 skrev Leo Izen: > On 8/17/23 08:59, Tomas Härdin wrote: > > ons 2023-08-16 klockan 01:20 -0400 skrev Leo Izen: > > > By default the OpenEXR decoder outputs linear light pixel data by > > > applying a gamma=1.0 transfer (i.e. a no-op). When it does so, it > > > should tag the data as linear so color-managed filters or other > > > tools > > > can work with it correctly. > > > > > > Signed-off-by: Leo Izen > > > --- > > > libavcodec/exr.c | 2 ++ > > > 1 file changed, 2 insertions(+) > > > > > > diff --git a/libavcodec/exr.c b/libavcodec/exr.c > > > index fae1d08ab0..518066facf 100644 > > > --- a/libavcodec/exr.c > > > +++ b/libavcodec/exr.c > > > @@ -2088,6 +2088,8 @@ static int decode_frame(AVCodecContext > > > *avctx, > > > AVFrame *picture, > > > > > > if (s->apply_trc_type != AVCOL_TRC_UNSPECIFIED) > > > avctx->color_trc = s->apply_trc_type; > > > + else if (s->gamma > 0.f && s->gamma < 1.0001f) > > > + avctx->color_trc = AVCOL_TRC_LINEAR; > > > > I'm going to be difficult here and point out that gamma=0.1 is > > not > > linear. It's probably linear *enough* most of the time, but also > > 1.0 > > can be exactly represented by float so an equality check seems > > appropriate. > > This exact check exists elsewhere in the source file. There's a > branch > where it sets up a LUT if gamma is not between those values, and has > a > no-op track otherwise - so in the event you request 0.5 or > something > of that form, the code that does the color conversion treats it as > 1.0f. Alright. I just find myself wondering how gamma could ever become some value that is close to 1.0 but not quite equal. /Tomas ___ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-devel] [PATCH] avcodec/exr: tag gamma=1.0 output as linear light
On 8/17/23 08:59, Tomas Härdin wrote: ons 2023-08-16 klockan 01:20 -0400 skrev Leo Izen: By default the OpenEXR decoder outputs linear light pixel data by applying a gamma=1.0 transfer (i.e. a no-op). When it does so, it should tag the data as linear so color-managed filters or other tools can work with it correctly. Signed-off-by: Leo Izen --- libavcodec/exr.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/libavcodec/exr.c b/libavcodec/exr.c index fae1d08ab0..518066facf 100644 --- a/libavcodec/exr.c +++ b/libavcodec/exr.c @@ -2088,6 +2088,8 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *picture, if (s->apply_trc_type != AVCOL_TRC_UNSPECIFIED) avctx->color_trc = s->apply_trc_type; + else if (s->gamma > 0.f && s->gamma < 1.0001f) + avctx->color_trc = AVCOL_TRC_LINEAR; I'm going to be difficult here and point out that gamma=0.1 is not linear. It's probably linear *enough* most of the time, but also 1.0 can be exactly represented by float so an equality check seems appropriate. This exact check exists elsewhere in the source file. There's a branch where it sets up a LUT if gamma is not between those values, and has a no-op track otherwise - so in the event you request 0.5 or something of that form, the code that does the color conversion treats it as 1.0f. - Leo Izen ___ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-devel] [PATCH] avcodec/exr: tag gamma=1.0 output as linear light
ons 2023-08-16 klockan 01:20 -0400 skrev Leo Izen: > By default the OpenEXR decoder outputs linear light pixel data by > applying a gamma=1.0 transfer (i.e. a no-op). When it does so, it > should tag the data as linear so color-managed filters or other tools > can work with it correctly. > > Signed-off-by: Leo Izen > --- > libavcodec/exr.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/libavcodec/exr.c b/libavcodec/exr.c > index fae1d08ab0..518066facf 100644 > --- a/libavcodec/exr.c > +++ b/libavcodec/exr.c > @@ -2088,6 +2088,8 @@ static int decode_frame(AVCodecContext *avctx, > AVFrame *picture, > > if (s->apply_trc_type != AVCOL_TRC_UNSPECIFIED) > avctx->color_trc = s->apply_trc_type; > + else if (s->gamma > 0.f && s->gamma < 1.0001f) > + avctx->color_trc = AVCOL_TRC_LINEAR; I'm going to be difficult here and point out that gamma=0.1 is not linear. It's probably linear *enough* most of the time, but also 1.0 can be exactly represented by float so an equality check seems appropriate /Tomas ___ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-devel] [PATCH] avcodec/exr: tag gamma=1.0 output as linear light
LGTM ___ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
[FFmpeg-devel] [PATCH] avcodec/exr: tag gamma=1.0 output as linear light
By default the OpenEXR decoder outputs linear light pixel data by
applying a gamma=1.0 transfer (i.e. a no-op). When it does so, it
should tag the data as linear so color-managed filters or other tools
can work with it correctly.
Signed-off-by: Leo Izen
---
libavcodec/exr.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/libavcodec/exr.c b/libavcodec/exr.c
index fae1d08ab0..518066facf 100644
--- a/libavcodec/exr.c
+++ b/libavcodec/exr.c
@@ -2088,6 +2088,8 @@ static int decode_frame(AVCodecContext *avctx, AVFrame
*picture,
if (s->apply_trc_type != AVCOL_TRC_UNSPECIFIED)
avctx->color_trc = s->apply_trc_type;
+else if (s->gamma > 0.f && s->gamma < 1.0001f)
+avctx->color_trc = AVCOL_TRC_LINEAR;
switch (s->compression) {
case EXR_RAW:
--
2.41.0
___
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
To unsubscribe, visit link above, or email
ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
