[argyllcms] Using BtoA1 table with rendering intent absolute

  • From: John Weissberg <jw@xxxxxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Thu, 06 Sep 2007 12:01:19 +0200

Consider the following case: Converting from Lab -> CMYK using the BtoA tables of an ICC profile with "Absolute Colorimetric" as a rendering intent.

As I understand it, the ICC profile does not contain an Absolute colorimetric BtoA table. Rather, it will use the relative colorimetric BtoA table, along with whitepoint data, for any look-ups it makes.

Can anyone explain what algorithm is used for these conversions between relative and absolute colorimetric?

Is it simply adding/subtracting the DeltaE between the whitepoint and 100,0,0 ? Is delta value added for all points in the color space? Only for points where L is above a certain limit?

Any information is appreciated.

John Weissberg
PerfectProof - Accuracy Made Easy


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