[argyllcms] Re: icmColorantTableVal_write: write of PCS coord failed
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Wed, 10 Jun 2009 09:48:32 +1000
Gerhard Fuernkranz wrote:
Hi Graeme, thanks for your analysis. So I need to send my monitor back,
because it is out of gamut ;-)
Yes, that's one solution :-)
I was still wondering why there is any need to use CIELAB and not XYZ
(since both, src and dst profile have XYZ PCS) but a brief look into the
ICC spec reveals that for a device link only CIELAB numbers are
permitted in the colorant tables :-(
I was thinking that since V4 re-defined 16 bit Lab encoding, it
was rather a pity that all the ICC did was fiddle 0xff00 to 0xffff
for a 0.4% change, rather than doing something useful such
as allowing for real world colorants outside the V2 Lab gamut.
Of course the implication is that you can't create an accurate LUT
based L*a*b* PCS profile for the XL20 either.
You're right, obviously that's yet another implication. Unfortunately
the device is not perfectly additive either (it's still an LCD display),
limiting the accuracy of a matrix/trc model as well.
So an cLUT based XYZ PCS profile is what's needed.
cheers,
Graeme Gill.
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