"Fredrik Eriksson" <noo### [at] nowherecom> wrote:
> I am not sure if this is what is causing your problems, but PC software
> has a tendency to assume that the monitor has a gamma of 2.2. Adjusting
> your monitor to make it have a gamma of 1.8 can make such software produce
> bad results.
>

Yet both .bmp and "unaltered" .png image_map images look identical on both
my PC and Mac (both monitors set to gamma of 1.8), in both versions of
Photoshop and in the final POV rendered scene on the PC. It's only the
"altered" .png file that causes problems.

>
> > I've purposely left out the "use assumed_gamma of 1.0" suggestion
> > altogether
>
> I take this to mean that you have tried it, and it made no difference....
>
Actually, no. I'm still not totally convinced of its usefulness...mainly
because I'm STILL trying to understand its pros and cons.  The set-up I now
have seems to "work for me, " so I haven't gone that route yet.  Although,
I do (sort of!) understand that a scene file to be shared with others may
need it, for rendering consistency.
>

>
> Have you examined the files to see what the gamma chunk says?

I have to admit ignornace there; how does one go about doing that?
>
>
> > Changing Photoshop's gamma to 1.45 equalizes them. Strange.
>
> Note that the ratio 1.45/1.8 is very close to 1.8/2.2.
>
That's VERY interesting!! I didn't notice that before.

Thanks for the tips.

Ken

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