RE: Ink limiting on Ultrachrome
RE: Ink limiting on Ultrachrome
- Subject: RE: Ink limiting on Ultrachrome
- From: Angus Pady <email@hidden>
- Date: Thu, 27 Feb 2003 15:44:02 -0500
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Thomas Said:
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I've worked quite a bit with profiling printers with Ultrachrome inks
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lately, and have discovered problems, similar to the ones described in a
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recent thread about the profie curving in on itself. Essentially the output
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becomes unreliable in the shadows (closes down), if the ink isn't limited
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*enough*.
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If solid densities for each color are too high the profile just isn't
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working satisfactorily.
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Now the big question is how do you find the maximum allowable density for
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each ink?
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It is of course possible just to do trial and error profiling and change the
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linearisation in between, and then look at a Hex plot (or spider plot) and
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see if the ends start to curve in, but it would be great if the sweet spot
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could be found without having to build half a ton of profiles.
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Essentially, how do you find out at what point the inks start to "curve
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inwards" before building a profile - anyone?
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Best Regards
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Thomas Holm / Pixl ApS
Angus' Reply
My technique has been to first limit the inks by density. Cyan below
2.00 and Magenta below 2.00. Once that is done I work on my gray
balance using the RIPs curves. Then as a last step I print out a
stepped scale with C, M, Y & K in 5 percent increments. Measure this
with the Gretag's Measure Tool - not spectral. Import this
measurement file into Chromix Color Think 2.0 and look at the 3D
plot. Usually it is the Magenta and Cyan that need further reduction.
This 3D plot allows me to get a visual of where the ink is hooking
(Hue shift) or reversing (saturation reduction). Lastly I re-check my
densities to be sure I have a density higher than my target.
This technique is a real time saver and build much better profiles.
I have read on this list about the validity of the Lab space to
reduce inks. But so far I have no other method and this has been
helpful for me. I hope it helps.
--
Angus Pady
Digital Solutions
Richmond Hill,
105 West Beaver Creek,
Suite 3, Ontario
L4B 1C6
P: 905-764-6003
F: 905-886-6800
http://www.ColourManagement.ca
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