[argyllcms] Re: FWA overcompensation bug in spec2cie

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Thu, 15 Jul 2010 09:04:00 +1000

Alexey Gribunin wrote:
spec2cie.exe -i ref/D50_0.0.sp -f -o 1931_2 Test.ti3 Test_UVCut.ti3 #command 1

In Test_UVCut.ti3 I have both spectral and LAB values. I think, they should match but they don't!

Spectral values seems to be FWA compensated correctly. After converting spectrals to Lab with the following command: spec2cie.exe -i D50 -o 1931_2 -n Test_UVCut.ti3 Test_UVCut_CIE.ti3

You aren't doing the same thing though. The CIE values from the first
are with a D50_0.0.sp illumination (UV and some blue filtered out). For
the second, you are applying a D50 illumination, and the extra blue
in it results in different values. If you do a:

spec2cie.exe -i ref/D50_0.0.sp -o 1931_2 -n Test_UVCut.ti3 Test_UVCut_CIE.ti3

you should get the same values (although scale by 100 bug is
an issue!).

Graeme Gill.

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