Re: Absolute vs Relative Colorimetry in the ICC Profiles?
Re: Absolute vs Relative Colorimetry in the ICC Profiles?
- Subject: Re: Absolute vs Relative Colorimetry in the ICC Profiles?
- From: "Bruce J. Lindbloom" <email@hidden>
- Date: Fri, 21 Sep 2001 16:43:00 -0500
Roger Breton wrote:
>
Then the sentence that reads "coordinates of the output paper be *adapted*
>
to the PCS Illuminant" is wrong. Because, the value of the paper is the
>
absolute colorimetric measurement D50/2 off my Digital Swatchbook or
>
Spectrolino, not an adapted value, if I understand you Bruce.
I think what is meant by "coordinates of the output paper be *adapted* to
the PCS Illuminant" is that the media white XYZ value must be relative to
the PCS illuminant, namely D50. If this measurement was made relative to
some other reference illuminant, say D65, it must first be adapted to D50
before being used in the equations. Since your Digital Swatchbook
presumably is set up for D50, 2 degree observer (the SAME reference as the
PCS), then no adaptation is needed for the measurement before inserting into
the equations.
>
This logic is hard to decipher.
Agreed. There is a little recursion going on there.
--
Bruce J. Lindbloom, Pictographics Intl. Corp.