Re: [ gnuplot-Bugs-1575425 ] "with image" ignores gamma for postscript output (fwd)

[Petr M. <mi...@ph...>]

>> I'm guessing that the gamma correction is part of the palette created
>> in the PostScript file and the image code is not using the palette.
>> I'll investigate.  May not be a quick fix.
>
> Actually the fix might not be too bad.  Here is the issue:

Yes, gamma plays a role only for the gray palette (not for colour palette).

> I would like to keep the images condensed if possible.  Is there a way to 
> tell if the grayscale is linear from within post.trm?
> Or should I write a short little routine to verify it is?

It is when "pm3dGamma != 1.0/1.5", so just one "if" is sufficient.

Actually, there are two possibilities:

(1) apply the gamma by a ps code: then there should be a bit advanced filter 
when reading the image -- something like that in pm3dConvertToImageGray.awk

(2) apply the gamma when post.trm is writing the image numbers into the 
postscript file, and ignore pm3dGamma within the ps file

The case (2) seems very easy to to code, but maybe you find a solution to 
(1).

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PM