Operating system and graphics card
Windows7; Windows8.1; Gtx560; hd4000
Broken: 2.76 48f7dd6
Short description of error
Overlay blending mode works in rgb color space and should work in linear space.
Exact steps for others to reproduce the error
Blend two textures and compare results in Photoshop/Gimp/Krita/. Ive attached png file and blend for comparison. Notice that gimp uses some wrong math and result aint same as krita or photoshop. Even blender after gamma correction looks a bit off cause of algorith they use for gamma correction. I used gamma correction node 1/2.2 for rgb to linear convertion and x2.2 multiply for linear to rgb convertion back.
@It is broken in every place in blender that use overlay, like material creators/node editors/texture paint etc.
@Other blending modes that use math in linar space are broken too. But overlay is most useful so im reporting it first.
@tanget space normal maps used in provided picture are just examples, you can use any color image to reproduce bug.