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

[Ethan A M. <merritt@u.washington.edu>]

On Wednesday 11 October 2006 11:42 pm, Daniel J Sebald wrote:
> Daniel J Sebald wrote:
> The Adobe book indicates that gamma correction can be implemented 
> with what is called a transfer function (the second level of color mapping).  
> So, as an alternative, I simply added a line before the image definition 
> 
> if (sm_palette.colorMode == SMPAL_COLOR_MODE_GRAY)
>     fprintf(gppsfile, "%s{1.0 %g div exp} settransfer\n", space, sm_palette.gamma);

"settransfer" is Level 2 PostScript, so your patch needs to be check the
"level1" flag and/or check for support dynamically.








> 
> What this does is create the line below:
> 
>   gsave
>   {1.0 0.2 div exp} settransfer
>   875 4740 translate
>   4959 -4240 scale
>   100 10 8
>   [ 100 0 0 10 0 0 ]
>   currentfile /ASCII85Decode filter
>   image
> 
> I'll send you the patch separately so that you may place it on SourceForge.  [Would it be possible to change SF to allow attaching to someone else's bug report?]  Let me know if that works.
> 
> I'm guessing that transfer functions could be widened in scope.  So if you'd like to use a transfer function somehow rather than /pm3dGamma, let me know.
> 
> Dan
> 
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-- 
Ethan A Merritt
Biomolecular Structure Center
University of Washington, Seattle 98195-7742