Rune wrote:
>
> Image_maps should never be gamma corrected.

This would really be the best situation. There are so many broken
programs when it comes to png gamma. Adding another layer of confusion
in povray is asking for trouble.

In an ideal world povray could could do nothing for images tagged as
gamma 1 and reverse gamma other images. Then if someone wants as-is images
he tags it as gamma 1 in an image editor. But this doesn't really work
because of so many broken image editors.

I was going to test with povray generated png but it still writes
the wrong gamma in the png. I will use TweakPNG to manually set gamma 1
to the linear test image. (I would expect not using assumed_gamma or
using assumed_gamma=Display_Gamma would produce gamma 1 png.)

This is what happens now to the _image_map_:

map gamma   no assumed_gamma       assumed_gamma 1        assumed_gamma 2.2

    1         no correction         no correction            gamma 2.2

   2.2        gamma 1/2.2            gamma 1/2.2            no correction


So if you put gamma 1 in the png and use assumed_gamma 1 or don't use
assumed_gamma the map is used as-is. Or you set:
map gamma=assumed_gamma=Display_Gamma.

Maybe it's easiest not use pngs as image maps :)


_____________
Kari Kivisalo

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