Am 01.12.2013 06:11, schrieb Cousin Ricky:
> I implemented gamut mapping in Ive's spectral rendering rig, based on method 2
> of CIE.inc in Lightsys IV.  Values above 1.0 are still clipped (which can
> distort the hue).  Attached are renders of a modified version of Prism.pov.  As
> you can see from the Osram render, there are still some bugs to be worked out
> for brighter values.
>
Coincidental I'm just about to release version 0.2 (within the next few 
hours, just one more example scene to render) so in case you are willing 
to share your addition (AFAIR gamut mapping was on my to-do-list anyway) 
your contribution would be quite welcome.
Note that HDR values are not addressed by gamut-mapping but are again an 
art of its own. There are a lot algorithms out there like "local 
contrast mapping" by well known Greg Ward and also "adaptive logarithmic 
mapping" or "gradient domain mapping" just to name a few ;) and there is 
no way to say one of them is the best - it usually depends on the kind 
of image to process.
Personally I do prefer to do stuff like this as post-processing.

> I made one change from the algorithm in MapGamut(): when finding the lowest of
> the RGB channels, I used <= instead of <, because the latter would always return
> the blue value if the red and green happened to be identical.  (You might want
> to look into that, Ive.)
>
Will do, and thanks for the hint.

-Ive

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