I have played a bit with the gamma and the transformation a linear curve can get by applying gamma.
Gamma (Yellow): y= x^Gamma
Red linear: y= 0.8x+0.10
Green linear: y= 0.8x+0.20
Blue linear: y= 0.8x+0.25
Red corrected curve: y=0.10-(0.8x+0.10)^Gamma
Green corrected curve: y=0.20-(0.8x+0.20)^Gamma
Blue corrected curve: y=0.25-(0.8x+0.25)^Gamma
I have not yet an idea what it means, nor am I sure if have applied correct x and y values, but if I'm not mistaken values from gamma acrobatics are normalized to values between 0 and 1.
This is as a help for thinking what might have happened above.
No idea if it has any declarative value.
I also am not sure if I did the subtraction correctly.
Ideas about the formulas?
(Rendering done with POVRay 3.7 beta)