Re: ACE in PSCS2
Re: ACE in PSCS2
- Subject: Re: ACE in PSCS2
- From: Chris Murphy <email@hidden>
- Date: Tue, 14 Jun 2005 20:00:48 -0600
On Jun 14, 2005, at 7:51 PM, Chris Murphy wrote:
Broken and different? What exactly are we talking about?
Perhaps I'm answering my own question...
ACE in the CS2 applications ignores a non-D50 wtpt tag in display
profiles. Editing/intermediate spaces are display profiles and until
ICC spec v4 it was rather vague how to handle them. v4 says that
display profiles always have a D50 wtpt tag. If the actual white
point isn't D50 then the primaries get chromatically adapted to D50,
and the chromatic adaptation tag is required so that it's possible to
reverse the chromatic adaptation used.
Anyway, ACE in the CS2 applications is essentially treating all
display profiles this way. You'll also notice a huge difference in
RGB to CMYK conversions where the source space white point is D65.
Previously you'd get hideously blue white (cyan and magenta scum
dots) conversions using AbsCol. That doesn't happen anymore.
Chris Murphy
Color Remedies (TM)
www.colorremedies.com/realworldcolor
---------------------------------------------------------
Co-author "Real World Color Management, 2nd Ed"
Published by PeachPit Press (ISBN 0-321-26722-2)
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