[argyllcms] Re: icmColorantTableVal_write: write of PCS coord failed
- From: Gerhard Fuernkranz <nospam456@xxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Wed, 10 Jun 2009 00:17:06 +0200
Graeme Gill wrote:
> The problem is that there are real world colorants with color values
> outside the ICC L*a*b* PCS range,
Hi Graeme, thanks for your analysis. So I need to send my monitor back,
because it is out of gamut ;-)
[no, of course I certainly won't do that - but indeed, subjectively I
was not prepared that any of my monitor's colorants might be beyond +/-128]
> so your source profile is in XYZ PCS and in trying to create colorant
> tables in the link in L*a*b* PCS, the XYZ can't be encoded. In this
> case it's the green primary that is out of encoding range.
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 :-(
> 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.
Best Regards,
Gerhard
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