Based on extensive testing, this gives matching HDR brighness across most
application, with both PNG and AVIF. Video remains at 100 nits as that
appears to tbe convention there.
This is implemented by adding two modified PQ and HLG color spaces to the
OCIO config on startup, and for the specific cases of image save and loaded
these will replace the regular PQ and HLG color spaces.
This was chosen rather than adding them as color spaces in the OCIO config,
so that it can work for any config with appropriate interop IDs, including
the ACES config. Additionally, it would be unclear how to make this work with
view + display transforms, we wouldn't want to burden the users with having
to pick a different display depending if they are saving images or video.
Ref #145855, #144911
Pull Request: https://projects.blender.org/blender/blender/pulls/146888
df12a448ba