Re: preview/photoshop
Re: preview/photoshop
- Subject: Re: preview/photoshop
- From: Ross Peterson <email@hidden>
- Date: Thu, 13 Jan 2005 08:46:47 -0600
Thank you very much for taking time to provide that explanation Chris.
I suspected something along those lines but was not confident in
putting it to paper.
On Jan 13, 2005, at 7:16 AM, Chris Murphy wrote:
There are a couple of explanations. If the source and destination
(display) profile are the small, simple, matrix-based profiles the CMM
plays a huge role in gamut mapping and probably accounts for most of
the difference.
So would the introduction of a LUT based display profile (Optix XR Pro)
affect the outcome significantly?
There was a recent post to this list suggesting that PS "mishandles"
LUT profiles in some instances. Any comment on that?
Do you know how the Apple apps handle LUT based display profiles?
Photoshop always uses ACE as the CMM when performing display
compensation. Photoshop also uses Relative Colorimetric rendering to
the display. Preview *converts* tagged images upon being opened, and
always uses the Apple CMM. I'm not sure what intent it defaults to but
it could be the profile default which is often Perceptual.
If the source profile is an input or output profile (scanner profile
or printer profile for example), Photoshop is using Relative
Colorimetric plus black point compensation to the display. Whatever
intent Preview is using, it's not using black point compensation.
So in both of these cases you can be virtually assured of some
differences between how the same image is displayed in Photoshop and
Preview (or any other application that's unable to use ACE).
Thanks again for your time,
Ross S. Peterson
Chris Murphy
Color Remedies (TM)
www.colorremedies.com/realworldcolor
-------------------------------------------------------------
Co-author "Real World Color Management, 2nd Edition"
Published by PeachPit Press (ISBN 0-321-26722-2)
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