[argyllcms] OT Rambling Profile Questions
- From: Idea Digital Imaging <qcore@xxxxxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Fri, 7 May 2010 20:53:24 +0100
Not specifically Argyll-related but hopefully OK for the list...
I've been supplied with a profile for an uncoated paper that is
behaving oddly.
The profile is here: <http://inside.rgb2cmyk.com/images/profile.zip>
The initial problem is that the images I'm working with have critical
neutrals including black to grey vignette backgrounds etc and there's
no GCR to help me in this profile. I've created a couple of variants
in Profilemaker (GCR4 and MaxK) which give better results (I have used
Argyll for this in the past but find adjusting black generation in
Profilemaker a lot easier).
I've created device links in Argyll (perceptual intent, gamut mapping
from source to destination profile) and the RGB to CMYK conversions
are looking great.
But then I find that half of the images can only be converted in
Photoshop because they are layered and need to retain those layers
during the conversion. There are no gamut issues with these images but
I do need to use a perceptual conversion because it usually provides
more shadow detail with uncoated papers.
The odd thing is that the relative conversion looks fine in Photoshop
but, when I select perceptual. all of the yellow drains out of the
neutrals and I get a nasty looking, cold result :(
So, my first question is: Why does a perceptual conversion in
Photoshop using this profile and the adapted versions I made in
Profilemaker remove so much yellow from the images compared to
relative intent? (The device links I made with Argyll don't do this)
And the second question is: What's the easiest way to stop this from
happening so that I can get perceptual conversions in Photoshop that
look more like my Argyll device link conversions?
And the third question arising from puzzling over this odd profile
behaviour is: How do the different vendors of profile making software
deal with perceptual conversions? Is there an established method or is
it secret sauce?
They say that a "problem shared is a problem halved" -- which could be
very useful as I've got to separate 128 images and output 9 A1 FOGRA
proofs by Monday afternoon...
--
Martin Orpen
Idea Digital Imaging Ltd
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