re: ink restrictions #1
re: ink restrictions #1
- Subject: re: ink restrictions #1
- From: Peter Henry <email@hidden>
- Date: Wed, 20 Dec 2000 16:51:41 +0100
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Message: 3
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Date: Mon, 18 Dec 2000 19:27:03 -0700
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From: David Wollmann <email@hidden>
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Reply-To: email@hidden
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Organization: Luna Vista Imaging
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To: ColorSync <email@hidden>
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Subject: re: ink restrictions
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Do you mean the >100%< Red, Green, and Blue patches? So, rather then
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using the >L< patches of the darkinkrestriction.tif, you simply observe
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how the Red, Green, and Blue 100% patches dry, and then adjust the
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threshold for m3, c3, and Y as needed?
[Peter Henry] yes this is the way. I don't use the L's because the
intention of these was best calibration
without icc profiling. the icc's makes that job for getting the best
gray much better...
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If these patches are too wet and
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taking to long to dry, do you reduce all 3 equally? I ask because yellow
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always seems to produce a lower Dmax, with flatter density curve versus
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the other inks. I've also noticed that if the yellow is set too high it
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will sit on top the blacks causing them to appear greenish.
[Peter Henry] yes true, very often equally. an idea could be having
the yellow approx 0.3D lower than the rest. especially when pigment outdoor
inks are used.
but anyway should the profile be able to prevent the greenish output
in the blacks. otherwise in the worst case you have to make some test
series. but it never happend to me...
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Being on this side of the pond ;-), I was wondering if using SWOP max
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densities might help give an idea of where I'm at, and perhaps help
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determine if I've gone below these >standard< Dmax settings.
[Peter Henry] yes at least this :-) my experiance is that the
offset densities are too low for the inkjet printer and
you are getting weak colors and strong colorcorrection in the hues
later on after profiling
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The Onyx manual seems to raise more questions then it answers when
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trying to set Ink Restrictions. This step does seem important since this
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establishes the foundation for everything that happens later.
[Peter Henry] true! the problem is that the pure dens value is not enough
to describe the color we really want to see in the max areas, due to the
fact that the offset inks and the inkjet inks are nearly comepletely
different with different properties. What we rather need is a Lab value and
a tolerance. (see the mail from Henrik Holmegaard
Subject: Inkjet profiling ABC_1)
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Well, I need to rush right out and get myself a Raster Microscope, my
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chemistry set never came with one of those! ;-) Must be a cool tool,
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but sounds expensive too. What about a strong loupe?
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[Peter Henry] yes ;-) a stong loupe should do the job too...
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100%... Meaning that the light and medium inks would be set to 100% of
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the value of the reduced dark ink, right? It sounds generally you do set
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the lighter shades of ink to a value 10% below the dark inks, and with
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the ColorSpan printers, sometimes it is okay to set the light values
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higher then the others, logic aside.
[Peter Henry] yes I guess you understood it right. an example ist
c3=30% c2=100% (or 90% like onyx recommends) and c1=100% (or 90% like onyx
recommends)
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When using the darkinkrestriction.tif how to you select your black
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patch?
[Peter Henry] I don't know how you mean this? the black is one
channel so I set that value of k3 in that way that it dries properly and it
has sufficient density in order to get rich and deep solids and letters
etc...
could be around a dense of 2.0D
hope that helps a bit
Peter
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Gretag Professional Imaging Division GmbH
European Management Technical Sales Support
72336 Balingen