Re: LAB as working/interchange space
Re: LAB as working/interchange space
- Subject: Re: LAB as working/interchange space
- From: Chris Cox <email@hidden>
- Date: Wed, 30 May 2001 14:06:01 -0700
At 1:50 PM -0700 5/30/01, email@hidden wrote:
Message: 5
Date: Wed, 30 May 2001 08:25:36 -0400
Subject: LAB as working/interchange space
From: Roger Breton <email@hidden>
To: <email@hidden>
CC: <email@hidden>
Roger Breton wote:
So there are "CIE" Lab and "ICC" Lab. Different encodings. OK. How about
Photoshop's own Lab? Which flavor of Lab is it exactly? Apart from the fact
that everyone knows that it is D50/2?
To which Chris Cox replied:
Photoshop uses ICC LAB.
The differences in LAB values could be accounted for by a number of
things: intent, Black Point Compensation, use of different CMMs
> (using different intermediate representations), etc.
To which Roger Breton adds:
There are no transformation involved here, Chris. The experience I relate is
that of displaying an already converted CMYK image in Photoshop 6 as opposed
to opening the same image in LinoColor, ProfileEditor and ColorFlow!
Must I point out that CMYK->LAB is also a conversion, and also has an
intent, and has a choice of black point compensation, and has a
choice of CMM?
If I
understand correctly, all these apps - including yours - all work off the
same ICC profile, then, to calculate the displayed Lab values? So, the
difference can only stem from application differences in interpreting the
profile tags, right?
Same profile, different math, different preferences -- of course it
can produce different results.
Chris