Mix node has non-linear behavior in the compositor #120713
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Reference: blender/blender#120713
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System Information
Operating system: Win 11
Graphics card: RRTX 2070
Blender Version
Broken:
f789619e65Short description of error
The mix node especially the multiply operation shows some non-linear behavior in the compositor, the real affect start being evident after getting closer to 1.0, definitely not it is not linear mixing.
Look at the difference between 0.25 all the way to 0.75 (the difference is barely visible) v 0.75 to 0.9 and 0.9 to 1.0
0.25
0.50
0.75
0.9
1.0
Exact steps for others to reproduce the error
Load the attached .blend
Play with the mixing values, color profiles etc
Mix node has noin linear behavior in the compositorto Mix node has non-linear behavior in the compositorIsn't this because the math is being done in a linear-light space? Unlike perceptual color spaces like sRGB where intensity is linear with perceived intensity, linear-light spaces have intensity linear with the physical amount of light, which perceptually makes them have way too much white.
It's the same reason a Color Ramp between black and white looks non-linear.
@scurest Sure, but the intended effect is not there and makes it hard to control the mixing. The user should feel like the mixing is "linear" and it feels like the actual mixing starts near to the end.
Okay, but literally all of Blender works this way, from every single color math node, to color pickers, to vertex painting...
Sure, I am not saying that is wrong, but it would be nice if the mixing has an option to make the mixing feel more linear when the view transform is set to non-raw. The other option is to make sure everything is linear/raw color space and use raw view transform.
@kursadk I believe blender assumes the whole process happens in linear values and only when outputting final image it is then converted to whatever output color space. So As a way to get around it, you could add two math nodes one before and one after the mixing operation and give it a power of about 2.2, so it's closer to the non-linear blending you've used to.
Closing this for now since it's not really a bug with blender. If you'd like to make a feature request, you can check out RightClickSelect. Thanks!