In article <opsas96dogefp2ch@news.povray.org>,
 "Phil Cook" <phi### [at] nospamdeckingdealscouk> wrote:

> MG1 without gamma, MG2 without gamma: MG2 darker image within MG1
> MG1 with gamma, MG2 without gamma: MG2 darker image within MG1
> MG1 without gamma, MG2 with gamma: Match colours
> MG1 with gamma, MG2 with gamma: Match colours.

I think I see what's going on...POV writes the gamma value to the PNG 
file and applies it to the read files, whether gamma correction is used 
or not. Also, the value it writes is 1.0/opts.DisplayGamma, which I'm 
pretty sure is not what it should write...I think opts.GammaFactor 
(assumed_gamma/display_gamma) would work better, but I'll have to look 
into it further.

Also, it appears to be doing gamma correction within pnglib, which only 
uses limited-precision fixed point color values. I'm pretty sure it 
would be better to do it on the native floating point colors.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: <chr### [at] tagpovrayorg>
http://tag.povray.org/

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