[argyllcms] Re: AW: Re: Question about IT8 reference data
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Tue, 9 Jun 2020 09:31:34 +1000
Hermann-Josef Röser wrote:
Hi,
I had calculated the Lab and XYZ values in the reference table from the
transmission data of the target and the tungsten spectrum. So I do not see,
why I should need any additional spectral data. Also the documentation
offers the option of choosing the tungsten spectrum with -iA. So I had
assumed the spectrum was internally available.
You can't have it both ways. Either you compute the illuminant A
XYZ values and feed them into colprof, or you feed spectral
values in and tell colprof to compute the XYZ values under illuminant A.
Yes, colprof has the spectrum of illuminant A. But there is nothing
to do if you don't supply spectral measurements for that illuminant
to act on.
If you are supplying the XYZ values, then colprof has no use for
the information that they were created under illuminant A.
cheers,
Graeme Gill.
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