Re: Digital Swatchbook and Dot Area
Re: Digital Swatchbook and Dot Area
- Subject: Re: Digital Swatchbook and Dot Area
- From: email@hidden
- Date: Fri, 28 Dec 2001 19:56:53 EST
In a message dated 12/28/01 4:36:24 PM, email@hidden writes:
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How can I use a Digital Swatch Book to Calibrate an Inkjet Printer.
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The ColorShop software has many functions the one's of interest area:
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CIE Lab values, Dot area, and Density.
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My goal is to send a 21 step swatch with CMYK steps, read each
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swatch, determine the density percentage and adjust my RIP.
This is not calibration, it is liniarization, but yes, its the first step in
color controlling your RIP.
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The problem I have is that when I read it and use the Dot Area tool
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the readings are too high ( plus 15-20% ). I just want it to say
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that the dot is, for example at 29%, when it should be 25%. That way
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I can adjust the RIP by 4 percent. Is this showing me dot gain
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values? Has anyone used this spectrophotometer/software for such a
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use?
Do you disbelieve it because the dot gain seems excessively high? Unless
there is some ink setup settings adjusting the inks in advance of
liniarization, then inkjet dot gain will generally run between thirty and
fourty five percent! Lots of small dots on an inkjet makes for more gain than
fewer larger dots, such as on most presses.
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Would I be better using something like ICCTools Pro?
You'll certainly need tools beyond ColorShop to build serious printer
profiles... but liniarization should be possible with what you have.
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Also, is it possible to use this tool to derive the optimum ink
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limiting setting for my RIP and paper combination? My understanding
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is that as a colour passes its maximum density it's hue will deviate.
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This would be evident in the Lab values, if I understand it correctly.
In some RIPs d-max is derived automatically from liniarization files, in
others you need to look at the Lab values yourself and determine d-max, and
input that number for each ink in the RIP interface. Puddling, rippling and
bleed through are factors here as well, but more for total ink than for
channel maximums.
C. David Tobie
Design Cooperative
email@hidden