HSL Blend Modes

[phrozen]

HUE blend mode produces the same effect on both Photoshop CS5 and GIMP. Current implementation reproduces both exactly.

SATURATION, COLOR, and LUMINOSITY blending modes have different implementations on Photoshop CS5 and GIMP. Current implementation of the library produces exactly the expected result from COLOR that GIMP uses and very similar results on SATURATION and LUMINOSITY. But the Photoshop CS5 algorithms have different results on all 3 of them.

To do:

• Match SATURATION and LUMINOSITY blend modes to the GIMP implementation, it may have to do with rgb to hsl transformations, maybe try different implementation (but... ¿why HUE and COLOR work as expected?).
• Find the correct Photoshop algorithms (if possible, ¿maybe reverse engineer them?) and implement them forking all functions that produce different results.