[argyllcms] profile: black generation
- From: Klaus Karcher <lists@xxxxxxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Sat, 31 Dec 2005 02:35:31 +0100
Hello Graeme,
thanks for the quick reply concerning xicclu. It behaves now as expected
(at least for my comprehension ;-).
Now I have a question regarding black generation (Singular Value
Decomposition):
Converting one of my favorite gamut mapping test images (the hull of a
RGB Cube) to CMYK, I noticed that although the composite view of the
result looks smoothly and coherently, viewing each canal separately
shows a undulating surface.
I've made a web page to illustrate this: see
http://digitalproof.info/argyll/k-test/
The only way to avoid the problem seems to set black generation to zero
or max -- increasing the quality parameter only reduces the wavelength
of the oscillation and using profile's new "-r" parameter or varying the
"smth" variable in gammap.c seems to have almost no influence on the issue.
Therefore I think the root of the problem must be somewhere in the svd
code. Do you have any hints on how it can be amended?
thanks in advance,
Klaus
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