vo_opengl: implement more HDR tonemapping algorithms

This is now a configurable option, with tunable parameters.

I got inspiration for these algorithms off wikipedia. "simple" seems to
work pretty well, but not well enough to make it a reasonable default.

Some other notable candidates:

- Local functions (e.g. based on local contrast or gradient)
- Clamp with soft knee (linear up to a point)
- Mapping in CIE L*Ch. Map L smoothly, clamp C and h.
- Color appearance models

These will have to be implemented some other time.

Note that the parameter "peak_src" to pass_tone_map should, in
principle, be auto-detected from the SEI information of the source file
where available. This will also have to be implemented in a later
commit.

1 files changed, 2 insertions, 0 deletions

diff --git a/video/out/opengl/video_shaders.h b/video/out/opengl/video_shaders.h
index 1f4496fbab..e43efadeb4 100644
--- a/video/out/opengl/video_shaders.h
+++ b/video/out/opengl/video_shaders.h
@@ -38,6 +38,8 @@ void pass_sample_oversample(struct gl_shader_cache *sc, struct scaler *scaler,
 void pass_linearize(struct gl_shader_cache *sc, enum mp_csp_trc trc);
 void pass_delinearize(struct gl_shader_cache *sc, enum mp_csp_trc trc);
 
+void pass_tone_map(struct gl_shader_cache *sc, float peak_src, float peak_dst,
+                   enum tone_mapping algo, float param);
 
 void pass_sample_deband(struct gl_shader_cache *sc, struct deband_opts *opts,
                         AVLFG *lfg);