Re: CMYK to CMYK Conversion question
Re: CMYK to CMYK Conversion question
- Subject: Re: CMYK to CMYK Conversion question
- From: Chris Murphy <email@hidden>
- Date: Wed, 4 May 2005 11:43:06 -0600
On Apr 12, 2005, at 8:30 PM, Joseph Yates wrote:
Recently we had a new profile made (again Chromix) for our new Asian
offset printer who also has the Creo Spectrum digital proofer.
We notice now when we convert from the old CMYK to the new CMYK
(either Relative Colormetric or Absolute) that the colors become very
unsaturated and the color balance is noticeable off as well. Some of
this can be corrected with a Saturation increase and Curves, but is
there a more accurate way to convert these legacy files to the new
profile, and get closer results? Do I need a Device Link Profile for
this? And how does one use this in Photoshop to convert the CMYK
legacy files?
I would not expect a DeviceLink profile to miraculously solve this
problem. It starts out merely as a concatenation of the two profiles
you're already using. Depending on what makes the DeviceLink, you can
add special handling for the black channel, or preserve channel purity
with or without scaling (anything yellow only stays yellow only, no
contamination). But if you're seeing a lack of saturation in reds, or
blues, or greens, and you have a gray balance issue - those kinds of
colors are still going to render as they would using the original
profiles to create the DeviceLink. So I'd investigate the two profiles
and find out why this is happening - some 3D modeling, and also test
each profile to see if there is excessive gamut compression occurring.
Are you getting good conversions with both profiles separately? If so
I'd be suspicious about the A2B table in the source profile,
responsible for defining how CMYK is mapped to the PCS. You might try
conversions using the saturation intent and see if that gets you an
improvement at all (unlikely but worth a shot).
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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