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.


> 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. Not  
surprising, given that you have calibrated both monitors to match.


> Now comes the problem...
> 4)  In PC, open the newly-created .png image in Photoshop 5.5, add  
> nothing
> to it,  and save it (as .png again.) Run POV scene with it.  Results  
> within
> POV: The image_map image is now darker, with more contrast...looking  
> like a
> major gamma alteration.

Sounds like the result of PS writing a gamma value of 2.2 to the file,  
even though it was created for gamma 1.8.

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


> 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.



-- 
FE

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