[Bf-committers] Luminance patches

[Antony Riakiotakis]

Hi,

We have quite a few functions to select luminance in our code.

Recently there were two patches to cleanup things.

https://developer.blender.org/D1082

https://developer.blender.org/D517

Seeing how developers still use any of the two in the code and how
there's really one correct formula for this it might be good to make
some decision about this.

Choises are - either we change this and break old files slightly or we
keep it and we have wrong histograms, tools and compatibility with
color management pipeline.

I am curious about what coders and artists think about the change
since it will influence both.