Cool. So we can be reasonably sure Brigitte's scene file has an
assumed_gamma statement other than 1.0 or that her image_map jpg specifies a
gamma correction. I was under the impression jpg files do not store gamma
correction information. If true when Brigitte correctly sets the
display_gamma and assumed_gamma to 1.0 she will see the proper color for her
image mapped object.

Is it still true many of the older textures shipped with POV-Ray will then
not be properly corrected for display because they expect an assumed gamma
of something like 2.2?

The documentation mentioned can be found at:
http://www.povray.org/documentation/view/3.6.1/218/

Bill

"Christoph Hormann" <chr### [at] gmxde> wrote in message
news:coa3g4$d45$1@chho.imagico.de...
>
> Did you read what i wrote?  This is perfectly normal and intended
> behaviour.  POV-Ray applies gamma correction to the rendered image
> according to the display_gamma setting (which is usually 2.2 on PC
> Windows/Linux) if an assumed_gamma statement is present in the scene.
> This is explained in detail in the docs.  Your numbers comply with this
> since
>
> (94/255)^(1/2.2) = (162/255)
>
> For image maps you therefore have to use images without gamma correction
> (i.e. linear images).  If your image is gamma corrected (like when you
> get it from the web or a (cheap) digital camera) use the gamma
> correction function of your imaging program for this.
>
> Christoph
>
> -- 
> POV-Ray tutorials, include files, Sim-POV,
> HCR-Edit and more: http://www.tu-bs.de/~y0013390/
> Last updated 23 Sep. 2004 _____./\/^>_*_<^\/\.______

Post a reply to this message