[argyllcms] Re: FWA overcompensation bug in spec2cie

  • From: Alexey Gribunin <Gribunin@xxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Thu, 15 Jul 2010 13:19:12 +0400

Hello Graeme!

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

Yes, it's clear. If I will do it, I will get Lab values compensated two times.

But I need it compensated only once, in one step like this:
spec2cie.exe -i ref/D50_0.0.sp -f -o 1931_2 Test.ti3 Test_UVCut.ti3

Again, the problem happens here, in this command. Test_UVCut.ti3 contains both spectral and LAB values and they are different. Spectrals are compensated with D50_0.0 only once, but Lab values two times because Lab calculated from spectrals with D50_0.0.sp again.

Best regards,
Alexey Gribunin,
UNIT Color Technologies,
Moscow, Russia.

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