Image_maps using png images are gamma corrected, which is bad, because the
entire image of the scene is also gamma corrected, so the image_maps are
gamma corrected twice. Image_maps should never be gamma corrected. This was
discussed years ago IIRC, but I can't find the thread right now.

The scene below should illustrate the problem. When rendered as an animation
it places itself in its own image, and the gamma issue becomes obvious. Can
anyone confirm?

// save the code in a file "pnggamma.pov"
// command line settings:
// +kff4 +kc +fn
background {rgb 0.7}
#default {finish {ambient 1}}
plane {y, -5 pigment {rgb 0.5}}
#declare Frame = ceil(clock*4-0.5);
sphere {<-1.1,0,3>,0.5 pigment {red 0.7}}
#if (Frame>0)
   box {0,1
      #local Img =
      concat("pnggamma",str(Frame,1,0),".png")
      pigment{image_map{png Img}}
      scale <2,1.5,1.5> translate <-0.5,-0.75,3>
   }
#end

Rune
--
3D images and anims, include files, tutorials and more:
Rune's World:    http://rsj.mobilixnet.dk (updated Feb 16)
POV-Ray Users:   http://rsj.mobilixnet.dk/povrayusers/
POV-Ray Webring: http://webring.povray.co.uk

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