Re: GRACol: Very surprised at how c100 m100 is displayed...
Re: GRACol: Very surprised at how c100 m100 is displayed...
- Subject: Re: GRACol: Very surprised at how c100 m100 is displayed...
- From: Terence Wyse <email@hidden>
- Date: Thu, 22 Apr 2010 17:07:36 -0400
Hi Brian,
May depend on the rendering intent you have set in your color prefs or your soft-proof settings. Make sure it's absolute if your soft-proofing.
All I can tell you is that the "official" GRACoL Coated1 profile that you can download from the IDEAlliance web site is a very good one. I haven't studied the latest Adobe-supplied GRACoL profile to make a determination as to it's worth. I did perform a "round-trip" of the Adobe profile and compared it back to the original GRACoL dataset once but didn't find anything unusual (max dE error was <1.0).
The GRACoL colorimetry specs (based roughly on Fogra 39) are taken from "real" presses and assumes an average amount of wet ink trap for the overprinting solids. If you run a KCMY rotation and have better-than-average wet ink trap...or are running UV inks with inter-unit drying...you might experience more "efficient" magenta-on-cyan trap which would tend to go towards purple. All I can say is that the C+M you're seeing is probably "correct" but it may not match the same as your press...."your mileage may vary" in other words. I've done a number of G7/GRACoL press calibrations and can say that the C+M colorimetry in GRACoL seems to be reasonable.
Regards,
Terry Wyse
On Apr 22, 2010, at 4:14 PM, Pylant, Brian wrote:
> This may be a stupid question, but:
>
> I've been doing some testing with the GRACol profiles, and one thing I
> noticed today: when using GRACol (or either of the SWOP 2006 profiles), c100
> m100 is shown as a navy blue.
>
> My experience has been that this CMYK breakdown should result in purple, not
> blue. I know our presses would produce purple. And take a look at Pantone
> Process 184-1 -- I can't think of anyone who would call that color "blue" or
> even close to blue. I generally feel that when magenta is more than 75% (and
> certainly more than 80%) of the cyan value, the resulting color would be
> what most people would call purple.
>
> So, is this because a press that is running to GRACol specs would actually
> produce blue? Or is this a fault with the profile?
>
> Brian
>
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______________________________________
Terence Wyse, WyseConsul
Color Management Consulting
G7 Certified Expert
FIRST Level II Implementation Specialist
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