On 14 Apr 2003 14:11:34 -0400
ingo <ing### [at] tagpovrayorg> wrote:

> Though, sometimes I wonder why assumed_gamma is a Float and not a
> Bool. Gamma_correction yes/no.

  Because it is a correction value? IMHO, it is suposed to let you adapt
the image to the intended viewing conditions. I think I finally learned
how assumed_gamma is related to the typical "viewing gamma" on most
gamma tutorials like this one:

  http://www.w3.org/TR/PNG-GammaAppendix.html)

  If I'm not wrong, it works this way:
 
    viewing_gamma = pov_output_gamma * display_gamma

  where 

    pov_output_gamma = 1/(Display_Gamma_ini_setting/scene_assumed_gamma)

  and display_gamma is the gamma corrections of your display.

  So, with assumed_gamma 1.0 you end up with a viewing_gamma of 1.0,
suposing you have set properly your ini setting to the real gamma of
your monitor. The usual recommendation says you must use a "viewing
gamma" of 1.0 for bright environments, 1.25 for poorly light rooms, and
1.5 for really dark rooms. 

  Please, can someone confirm I'm not worng? 

-- 
Jaime Vives Piqueres
		
La Persistencia de la Ignorancia
http://www.ignorancia.org

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