[Gimp-developer] Some blend modes break in unbounded mode sRGB

[Elle Stone <ellestone ninedegreesbelow com>]

For Lighten only, Darken only, Multiply, Divide, and some of the other 
blend modes, results are *highly dependent* on the color space in which 
the blending is done. Removing clipping code doesn't fix the problem.

If the artist uses any of the color-space dependent blend modes:

* Editing an image in a large gamut color space such as ProPhotoRGB 
produces one set of colors.

* Converting the image to unbounded mode sRGB before editing it 
necessarily produces different colors - sometimes very different colors.

For concrete examples showing how Lighten only and Darken only are 
color-space dependent, see 
http://ninedegreesbelow.com/gimpgit/unbounded-srgb-lighten-darken.html

Can this problem be fixed? Is there a workaround such that an image can 
be converted from its source color space to unbounded mode sRGB, and 
then use the color-space dependent blend modes to produce the same 
colors that would have been produced if the image had been edited in the 
source color space instead of in unbounded mode sRGB?


Elle Stone