RE: How to make a linearization ?
RE: How to make a linearization ?
- Subject: RE: How to make a linearization ?
- From: Ray Maxwell <email@hidden>
- Date: Mon, 25 Aug 2003 09:45:55 -0700
Hi Peter,
The simple answer is to set the limits at a point where the density reaches
a maximum. Many people set ink limits in this way. However, you may cause
your color management software and profile making software to work overtime
to correct some problems you may introduce. As well as looking at density,
I suggest that you plot the a* and b* values for each color step wedge. You
just plot the a* vs. b* from you CIELab measurements. When you do this you
will find that some ink and paper combinations cause the Hue to change and
the chroma to decrease at the point that the inks reach saturation. You
should set you ink limits so that you don't go past the maximum chroma
point. Please note that this is another "rule of thumb". When we chose ink
limits for our systems we measure density and CIELab and then plot input
tint vs. density, a* vs. b*, and input tint vs. chroma. We look at the
level that causes mottling or slow drying of the inks. We look at color
drift when using different ink levels. What I am saying is that there are
many factors that can be examined before you can set the ink levels to what
may be their optimum values. However, looking at density and CIELab is a
good place to start. I would also suggest that if you are doing proofing of
offset presswork you use about 20% dot gain when you calibrate you inkjet
before profiling.
Hope this helps,
Ray
Creo
Ray Maxwell | Senior Color Systems Engineer, Inkjet Printing
4225 Kincaid Street | Phone (604) 451-2700 ext. 2004
Burnaby, B.C.
Canada V5G 4P5
IMAGINE CREATE BELIEVE
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From: Peter Baumbach
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Sent: Sunday, August 24, 2003 4:30 AM
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To: email@hidden
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Subject: How to make a linearization ?
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I am testing for the first time a rip that allows full
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control and wonder how a gamut maximizing and / or stable
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linearization is made. Are there any rules of thumb when to
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cut off each ink channel? Do you look for the maximum in
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density or for the largest chroma or for some combination of
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both ? If you cut off one channel what should be done with
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the others ?
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Thanks in advance,
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Peter
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peter baumbach - fine art photography
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http://www.pb-photo.net
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