Wrong(legacy) luminance formula in some plugins
Hi. I am not a native English speaker, so I apologize if I write with errors (I hope you can understand me).
It seems that some plugins use the wrong formula to calculate luminosity.
Perhaps somewhere else.
The coefficients used for NTSC RGB, for sRGB need others. You can find more details in this table: http://www.brucelindbloom.com/index.html?WorkingSpaceInfo.html
Or in the W3C specification: https://www.w3.org/WAI/GL/wiki/Relative_luminance Also, GEGL already uses the correct formula, for example:
This is easy to fix, and I can send a commit or attach a patch, but I think that opening the discussion first is a better way. Thanks for attention.