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Color space seems wrong while painting in image editor.
Confirmed, NormalPublicKNOWN ISSUE

Description

In the image editor add a new image and with default settings just do a red line paint over a green line paint.
Dark zone appear in the falloff between red and green. it should not be there and should stay clear, not dark.
I don't know why, but it looks like a color space issue.

dark falloff not ok in blender:

clear falloff ok in gimp:

blender 2.8
Windows 7

Event Timeline

In the Photoshop and Affinity Photo it looks the same with a dark halo,
it seems that GIMP mixes colors in linear space.

{F7649769}

https://ninedegreesbelow.com/photography/linear-gamma-blur-normal-blend.html

Bug!

But it’s a deep rabbit hole that requires attention.

The painting is nonlinear encoding math as a glance. There’s also possible alpha elements, but this will happen any time you apply light transport math to something that is nonlinear light encoded.

All manipulations must be done upon linear light ratios, which is not happening here. This cascades into deeper bit depth internal representation, and selectable transforms on a per UI basis.

This should have likely been tackled years ago, before coupling more problems on top of the stack. But alas, here we are. Probably better to try and tackle it now.

https://medium.com/the-hitchhikers-guide-to-digital-colour/the-hitchhikers-guide-to-digital-colour-question-9-why-the-f-ck-is-linear-light-important-for-a-48e32309b9ca

William Reynish (billreynish) lowered the priority of this task from 90 to 50.

Assigning to you then :) Feel free to re-assign.

Jeroen Bakker (jbakker) changed the subtype of this task from "Report" to "Known Issue".Jan 10 2020, 2:45 PM