Di Gama wrote:
> I am working on a POV-Ray project which involves loading an external image
> and re-displaying it with no color adjustment. I recently discovered that
> "ambient 1" with no light_sources is not enough; the picture comes out
> brighter than the original. I traced the problem to the picture below. The
> top band is POV-Ray's rendering of a smooth gradient black to white at
> ambient 1 with no light_sources. The bottom band is an unmodified gradient
> black to white made by Fireworks. I hold in doubt neither gradient, and I
> think the problem lies in how the object color is transformed into a final
> pixel color. What is going on, and how can I disable or counter this
> change?

Try looking up "assumed gamma" and "display gamma".

Basically, POV-Ray "ships" with display gamma set to 2.2 (on Windows) 
and you should set assumed_gamma in global_settings to 2.2 as well to 
make no gamma-changes on loaded pictures. This kinda doesn't work with 
PNG, depending if the gamma is encoded within it or not...

All in all, it's a slightly complicated matter, but experiment and 
you'll learn. :-)

Regards,
Tim

-- 
aka "Tim Nikias"
Homepage: <http://www.nolights.de>

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