Two renders of the same scene, the top with gamma correction and the bottom
without.  The rightmost pixels of each sphere are only 5% apart (244 vs.
232) but gamma correction makes the top light source seem much brighter.

For the discussion with similar subject in p.g. at
http://news.povray.org/povray.general/thread/%3Cweb.439a1b692d1f46002a1c213f0%40news.povray.org%3E/

I'm not making a point about which is right or wrong, just doing a little
excercise.

global_settings { assumed_gamma 1 }  // or not...
sphere {0 1
  texture {
    finish {ambient 0 diffuse 1}
    pigment {rgb 1}
  }
}
light_source { <100, 0, 0> rgb 1}
camera {location -3*z look_at 0}

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Download 'gammaball.png' (10 KB)

Preview of image 'gammaball.png'

Interesting. Personally I often use assumed_gamma 1 and brilliance 2 to get 
a smooth falloff like the lower image, but with the advantages of linear 
colour space.

-- 
Tek
http://evilsuperbrain.com

"Ard" <ard### [at] waikatoacnz> wrote in message 
news:web.43a0a486c3c8eadaed802ab30@news.povray.org...
> Two renders of the same scene, the top with gamma correction and the 
> bottom
> without.  The rightmost pixels of each sphere are only 5% apart (244 vs.
> 232) but gamma correction makes the top light source seem much brighter.
>
> For the discussion with similar subject in p.g. at
>
http://news.povray.org/povray.general/thread/%3Cweb.439a1b692d1f46002a1c213f0%40news.povray.org%3E/
>
> I'm not making a point about which is right or wrong, just doing a little
> excercise.
>
> global_settings { assumed_gamma 1 }  // or not...
> sphere {0 1
>  texture {
>    finish {ambient 0 diffuse 1}
>    pigment {rgb 1}
>  }
> }
> light_source { <100, 0, 0> rgb 1}
> camera {location -3*z look_at 0}
>
>


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