>    Render it with pov3.7 without and with the assumed_gamma, and you'll see
> the clear difference. Even though the mid-gray might technically speaking
> be a truly 50% gray, the gradient doesn't still look linear (what is
> supposed to be a smooth gradient fading linearly from white in the center
> to black in the border looks almost like a sphere).

The problem is it's mostly just coincidence that the traditional gamma 
2.2 better matches the human perception of "brightness" (IIRC it's 
nearer 3 than 2.2 for humans) than no gamma (ie 1.0).  This means that 
smooth gradients interpolated in gamma 2.2 space will *look* a lot more 
"linear" to humans than those interpolated in linear colour space.

There are other colour spaces designed specifically to match the human 
response (eg CIELAB), so I think the ideal solution would be for there 
to be a keyword to tell POV to use a "human-linear" colour space.  This 
would then work regardless of gamma setting (which shouldn't be abused 
to get a linear looking gradient, because it will mess up the other 
lighting calculations).

Anyway without such a feature, POV should be flexible enough to get what 
you want without resorting to messing about with gamma settings. 
(assuming your goal is a photorealistic scene, if not by all means 
fiddle with gamma if it gives you what you want)

Post a reply to this message