[argyllcms] Custom Illuminant

  • From: <robert@xxxxxxxxxxxxxxxxxx>
  • To: <argyllcms@xxxxxxxxxxxxx>
  • Date: Sat, 14 Jun 2014 12:09:54 +0100

Hello Graeme,


I've checked various documents, including this one
http://www.computer-darkroom.com/softproof/softproof_1.htm and Photoshop
does simulate paper color with all the rendering intents, as I can see when
I do a soft-proof.


I would really like to understand what Photoshop is doing. I have a contact
in Adobe who should be able to point me in the right direction. However
before doing that I would like to understand what is happening at the
profile level.


A print made from a profile that uses an sp file is identical to a print
made with a profile that does not use the sp file.  So I assume that the
BtoA (PCS to Printer) is at D50 and is not affected by the custom
illuminant.  Is that correct?


If the profile made with the sp file is used for soft-proofing, the paper
white is adjusted correctly (I've also tried different illuminants like A,
F5 etc, all appearing correct).  So I assume that the AtoB (Printer to PCS)
does take into account the custom illuminant.  Is that correct?


Does this apply to all the rendering intents, or only to Absolute
Colorimetric (as I think you said)?


Is this (or whatever method you use) also applied to FWA compensation (if -i
and -f both specify the custom .sp file)?


I've read your documentation and purchased your paper on FWA compensation,
but I still can't make much sense of what's happening.






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