Re: CMYK files
Re: CMYK files
- Subject: Re: CMYK files
- From: email@hidden (Lee Blevins)
- Date: Sat, 17 Feb 2001 17:01:44 -0500
- Organization: Digital Graphics, Inc.
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on 2/16/01 8:47 PM, mjt at email@hidden wrote:
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> I converted the CMYK files to my
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> working space before editing for output to the Roland.
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How? Since the original files had no embedded profile, what did you use as a
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source (hint, the CMYK Working Space you have loaded). That assumption about
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the origin of the CMYK may or may not be valid. Of course you have to guess.
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But before doing a conversion from CMYK to a Working Space, you should try
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and figure out if the assumption is close. Did the images look OK when
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viewed prior to the conversion? If not, the assigned profile is probably not
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close to what the files CMYK space is actually in.
We deal with the issue of cmyk colorspace a lot in our shop.
The way we look at the source is by determining what method the cmyk was
proofed at. For example, if the cmyk was output and proofed on
Matchprint, then we assume the source of the cmyk to be Matchprint.
So we would convert from Matchprint to RGB working space. Normally we
don't do this because we can just convert from cmyk to cmyk using
profile to profile. It's not very often that we really need to take an
image from cmyk to rgb, usually it's the other way around.
It's a major concern of ours as we look at large format inkjet printers
and rips. Can they work with the original data in cmyk. It would be
totally impractical to have to convert our data to rgb before
outputting. In fact, we would steer away from a system that worked that
way.
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> Is there a recommended
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> workflow to follow when confronted with vintage CMYK files?
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If you know the source of the CMYK, the conversions will be a lot easier and
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more accurate. With untagged files, it's a guessing game. Some suggest doing
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a conversion to LAB but I'd have to believe that Photoshop would need to
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make the same assumptions about the source to get to LAB so you may be in
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the same boat.
Here again, my suggestion would be to determine how the files have been
seen before. Were they printed on a press or were they show as Iris
proofs or what? However they were printed is the origin of their
profile.
It's a safe bet to use a common contract proofing system as your origin
since any disupute of the color in cmyk is usually resolved by
outputting and proofing on one of these systems. In the world of cmyk
printing people don't usually evaluate the color on monitor, they output
it and view the proof.