Re: ColorSync and PostScript printing
Re: ColorSync and PostScript printing
- Subject: Re: ColorSync and PostScript printing
- From: Rolf Gierling <email@hidden>
- Date: Mon, 7 Mar 2005 16:57:20 +0100
Prelimary for further discussion:
As far as I can see until now postscript printing using
ColorSync->Standard
in the printing options behaves like this:
Conventions:
source is the profile of the tiff image I used
destination is the profile for the printer assigned in ColorSync
Utility>Devices>Printers
If you print to a registered CMYK device and:
source and destination are the same, the numbers are unchanged,
if source and destination don't match, matching ocurs, but the numbers
are not what you get in Photoshop or with AppleScript. (see below)*
if source is untagged, Generic will be applied in both CMYK and RGB
(untagged to ISOcoated gives the same numbers as Generic to ISOcoated)
If the source is RGB, it gets matched to Generic CMYK first and is
then matched to the destination. (You can proove this by using
a manipulated Generic CMYK profile)*
If you print to a registered RGB device and:
the PPD says *DefaultColorSpace: CMYK, matching of RGB-data is
source -> GenericCMYK -> destination *
if the PPD says *DefaultColorSpace: RGB, matching of RGB-data is
source -> destination, but again the numbers aren't what I would
expect.*
*
I tried to provocate this behaviour in Logo Color Lab: Converting
colors from ColorMatchRGB to XYZ to ColorMatchRGB isn't the
same as from ColorMatchRGB to ColorMatchRGB, when the second
ColorMatch profile is a renamed copy to force the match. This thing
reminds me to the scumdot problem we all have seen a lot of times.
Conclusion:
Postscript printing using ColorSync is reliable if you use CMYK source
that is already matched to the destination.
You simply can't get reliable output if the source is in RGB.
Rolf
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Colormanagement
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Germany
Tel. +49 (0) 2 41 / 4 01 25 79
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