Re: CMM "interfering" with PS color picker? message 11
Re: CMM "interfering" with PS color picker? message 11
- Subject: Re: CMM "interfering" with PS color picker? message 11
- From: Greg Rettig <email@hidden>
- Date: Tue, 30 Jan 2001 15:00:21 -0500
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Terry,
I don't believe what you are seeing is a photoshop problem? Photoshop is just converting
with the profile you have chosen. Thus it wants to give you a minimum highlight dot at 1 to
2 percent, this you would most likely loose in a film work flow thus you would get the paper
white you are looking for. In a direct to plate work flow you would get the 1 to 2 percent
dot. The shadows I get from my profilemaker profiles(to digital matchprint) are not your
"normal scanner gray balanced shadows) they are normaly 75% ymc and 95%k for a total ink
coverage of 320%(give or take a few percent depending on the "black area" of the rgb image
in question. I do get good gray balance in photos and excellent results with the profiles
when scanning with a topaz scanner...lab to cmyk on the fly. The profile is just trying to
give you a good conversion from hightlight to shadow, with out loosing to much in the
process, both contrast, white to black and still maintain the color of your original. Thats
my view of it ... I look forward to being "corrected" or adjusted by the rest of the group
as to why all this happens....great question.
Greg Rettig
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Message: 11
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Date: Tue, 30 Jan 2001 12:59:53 -0500
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Subject: CMM "interfering" with PS color picker ?...
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From: Terry Wyse <email@hidden>
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To: Colorsync users list <email@hidden>, Color Theory
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<email@hidden>
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Ran into something a bit disconcerting in PS6 recently.
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Settings:
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RGB: Adobe98
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CMYK: custom "PressCMYK" ICC profile that I created using ProfileMaker 3.1.
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CMM: Heidelberg or Adobe.
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Select the "default" Black/White foreground/background option. Choose the
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White and view the Color Picker values.
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RGB = 255/255/255
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Lab = 100/0/0
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*CMYK = 1/1/2/0* (What's with that?)
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If I manually set CMYK = 0/0/0/0, the RGB then = 253/254/254
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I guess I'm confused why RGB=255/255/255 doesn't = 0% CMYK and, in fact that
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0% CMYK, when set manually, = something LESS than RGB=255/255/255.
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If I change to the Adobe CMM (I was using Heidelberg in the example above),
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I get different values but still not a pure white in CMYK.
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Oddly enough, if I try the same thing in PS5.5, I get the same results using
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the Heidelberg CMM but I *do* get 0%CMYK with the Adobe engine. Adobe engine
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changed slightly in PS6? Also, a change in rendering intent (relcol vs.
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percept.) made no difference.
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I also did some checking of the "Black" (RGB=0/0/0) and noticed a couple of
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things:
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1) changing CMMs results in a slightly different CMYK balance. For roughly
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the same total ink, the Heidelberg CMM tended towards less K and more CMY.
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The opposite was true of the Adobe CMM. The Adobe CMM gave me closer to what
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I had spec'd in the separation setup for the K limit in ProfileMaker.
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2) Although neither CMM gave me the Total Ink I had set in the separation
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setup (naturally may be a function of the total ink I was "requesting" vs.
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the amount of UCR/GCR I had spec'd), the Adobe CMM gave me on average about
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3-5% more total ink.
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I don't suspect that there's anything "wrong" with my profiles as they have
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been giving us excellent results in all cases.
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Inquiring minds need to know...
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Terry
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_____________________________
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Terence (Terry) Wyse
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PrePress Specialist
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All Systems Integration, Inc.
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781.935.3322 voice
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781.935.6622 fax
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http://www.allsystems.com
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email@hidden
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_____________________________
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