Jerry Anning wrote in message <36e7ec62.3365811@news.povray.org>...
>If you are using pigments from color.inc, remember that many of them
>were created before POV had gamma correction, mostly on pc's with
>gamma 2.2 or so, and are designed to look "right" with that gamma.
>Thus, if you use assumed_gamma 1.0 (the Right Thing to do), you will
>need to alter them accordingly.  This also applies to most of the
>other standard includes (woods, stones, metals etc.).  Here is a
>little macro I have used for the purpose.
>
>// Begin POV code
>
>#macro Fixcols(Badcol)
> color rgb <pow(Badcol.red, 2.2), pow(Badcol.green, 2.2),
>pow(Badcol.blue, 2.2)>
> filter Badcol.filter transmit Badcol.transmit
>#end
>
>// End POV code
>
>Just wrap it around the color to be adjusted thus, for example:
>
>pigment { Fixcols(HuntersGreen) }
>
>
>Jerry Anning
>clem "at" dhol "dot" com


I've converted colors from Metals and Stones, as well as the primitive
colors, and analysed the effects mathematically as well as empirically.  I
discovered that you need to apply the 2.2 factor to the Transmit channel as
well, for the colors of a layered texture to look the same (assuming I
understand Transmit correctly).  I'm not sure about Filter, since I don't
know how filter works mathematically, but I would guess that applying the
2.2 correction to that too is either also correct, or is at least closer to
the original if it can't match exactly.

There is also a difference in lighting, if you have more than one light
source.

I'll add my data and detailed conclusions to my web page on the subject,
over the next few days.

--John

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