[argyllcms] Re: xicclu -g predictability issue
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Mon, 31 Jan 2011 13:37:38 +1100
Gerhard Fuernkranz wrote:
Using a profile created from Elena's ofps2.ti3 data I did take a closer
look at a short line crossing one of the discontinuities (a straight
line in the source sRGB space, which is then converted with perceptual
intent to CMYK).
And it seems to happen at a location where CMYK colorants are crossing
very steeply. Note that the 101 CMYK points below spawn only a couple of
dE in total!
Right. So it seems that this is not a bug in the inversion
algorithm, but reflects the sudden shift in K vs. CMY at
that particular spot on the gamut boundary.
So possibly limiting the 1st derivatives may be a key to success?
The problem is that gamut has a priority that trumps any secondary
factor. A more complicated approach is needed to set a trade-off
between gamut volume and device value smoothness.
Graeme Gill.
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