Re:Kodak CMM in Photoshop
Re:Kodak CMM in Photoshop
- Subject: Re:Kodak CMM in Photoshop
- From: Steve Upton <email@hidden>
- Date: Sat, 21 Apr 2001 17:38:09 -0700
At 5:29 PM -0600 4/21/01, Chris Murphy wrote:
Chris Cox <email@hidden> writes:
It's a combination of problems in ColorSync and the Kodak CMM, and
could also be a bad profile (we're finding lots of profiles that
don't seem to grasp the ICC definition of white in 16bit LAB).
I don't think it's that simple because I've had the problem with all of
the CMM's, but less so with the Apple CMM, and almost none with the Adobe
CMM.
And you really should be using the Adobe CMM (ACE) for best results.
I've had a ProfileMaker 3.1.2 profile generate non-zero results with the
Adobe CMM; and then the exact same measurement data building a profile in
3.1.4 fixed the problemw with the Adobe CMM, but it remained with other
CMMs.
Now maybe one can effectively "blame" this on improperly built ICC
profiles, but I blame the CMM's (all of them) more than the profile. The
CMM should be smarter than the profile and not allow the profile (which
is just a text file afterall) to mandate a non-zero result with
perceptual, relative colorimetric, and saturation rendering.
I'm glad this issue has been opened as it prompts me to offer some of
my findings.
I wrote a quick routine to fix up the PCS whitepoint definition that
is (possibly) miss-specified in the GretagMacbeth profiles. Even with
this fixed white point they still create "scum dots" sometimes in
Photoshop.
This is not limited to GretagMacbeth's profiles - I just have them at
my disposal right now.
Should I write an additional tool in the Profile Medic part of
ColorThink that cleans up scum dots?
I have noticed that the curves in the Photoshop-bundled profiles are
"pegged" at the ends to avoid this problem.
Whataya think?
Regards,
Steve Upton
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