RE: A "simplified interpolation model" in Camera Raw?
RE: A "simplified interpolation model" in Camera Raw?
- Subject: RE: A "simplified interpolation model" in Camera Raw?
- From: "Tim Vitale" <email@hidden>
- Date: Tue, 17 Jul 2007 17:15:47 -0700
- Importance: Normal
> -----Edmund Ronald wrote-----
> Adobe Raw does not use ICC profiles, but interpolates between two
> simplified "Adobe profiles" established for the camera under two
> lighting conditions at opposite ends of the K scale.
They are ICC profile similar to Working Space profiles with white point and matrix-type
curves. They use the XYZ, PCS, and thus do not introduce the faults that are generated
when using the Lab, PCS, such as with input and output profiles. I think of them as
simpler and better.
Bruce Lindbloom points out that the use of Lab PCS causes, (1) yellows and (2) green to
desaturate, (3) some reds to go orange and (4) some blues to go purple
http://www.brucelindbloom.com/index.html?UPLab.html. I have also written on this, but
Lindbloom is the definitive resource.
Many folks consider the simple profiles used by ACR to be superior to input and output
profiles.
If you need to use an input profile with its Lab-PCS, be aware that they create problems
while they resolve others. The problems they create are easier to resolve, because
Lindbloom has made them predictable; but they are "by hand" corrections. I see these
problems all the time as desaturated yellows. I have only seen the shift to orange and
purple problem about 4-5 times. As far as I can tell, Lindbloom's "helper profile," which
could be used to correct for the non-uniform-Lab errors, can't be implemented until one of
the manufacturers builds-in the tool.
Tim Vitale
Paper, Photographs &
Electronic Media Conservator
Film Migration to Digital Format
Digital Imaging & Facsimiles
Preservation & Imaging Consulting
Preservation Associates
1500 Park Avenue
Suite 132
Emeryville, CA 94608
510-594-8277
510-594-8799 fax
email@hidden <http://briefcase.yahoo.com/email@hidden>
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