Re: Distiller 5 CSA to ICC matrix
Re: Distiller 5 CSA to ICC matrix
- Subject: Re: Distiller 5 CSA to ICC matrix
- From: olaf druemmer <email@hidden>
- Date: Sun, 6 May 2001 22:37:08 +0200
Hi,
what happens when
- a Photoshop EPS
- with PostScript color management turned on
- is distilled by Distiller
- at least when leave colors unchanged is turned on
is:
- PostScript color management is achieved through a CSA
- Photoshop 6 (I haven't checked other versions or apps) writes extra
info into the CSA, namely stuff like profile name, rendering intent,
creator of profile etc.
- Distiller 5 picks up that info and
- tries to find a profile on the workstation (in the various places where
ICC profiles live) that matches the extra information in the CSA
- if a precise match is found the matching profile is embedded into the
PDF and the resp. color values are left untouched
- thus we arrive at ICC based color space (something, which is very
useful from my point of view) with color values untouched.
- this works for gray scale, RGB and CMYK.
The only thing that is annoying is that we have to figure this out by
experimentation (in such an area I consider experimentation and
professionalism mutually exclusive...). I got some confirmation from
Adobe about this behavior but would rather prefer to have a precise
description of what is happening when.
Olaf Druemmer
>
--- Henrik Holmegaard wrote 5/6/01 4:49 PM: ---
>
Mauro Boscarol wrote:
>
>
>Do you mean a Photoshop 6 EPS file distilled by Distiller 5?
>
>
Also if you select PostScript Color Management and an ICC printer
>
profile and rendering intent say in Illustrator 9.
>
>
The AtoB1 intent (maybe AtoB0 also, I'm not sure yet) in the ICC
>
printer profile is converted into a CIEBasedDEFG CSA.
>
>
The PDF 1.3 specification doesn't implemented calCMYK / CIEBasedDEFG.
>
So Distiller 4 can't just leave the object as it is and bring both
>
object and color space specification into the PDF file. It has to
>
convert the object, so it converts the object into Lab, creating the
>
first half of a proofing transform.
>
>
Distiller 5 leaves the CMYK object alone and instead converts the
>
color space specification from CIEBasedDEFG to ICC. This way you have
>
a way ahead with the document.
>
>
>i.e., ih the case "TagICC UntagPSCM" ICC is ignored?
>
>
Yes, because PostScript doesn't support ICC profiles. Distiller is a
>
PostScript RIP, it only understands PostScript CSAs.
>
>
The weakness in creating PDF from Distiller (all versions) is that
>
you have to pass through a non-ICC process, and on the back end of
>
that process you can then tag ICC profiles. But only after you loose
>
your ICC spaces on the front end of the process.
>
>
This is why you need something like GretagMacbeth iQueue to
>
'normalize' your source color spaces into a single destination color
>
space. Then build your PDF and tag it with that color space.
>
>
A better way to create PDF 1.3 is from InDesign, though there are
>
still some problems left here.
>
>
>>
>
>> UntagICC TagPSCM in PS6 = ICCBased
>
>
>
>which ICCBased (there isn't a ICC in the Photoshop 6 file)?
>
>
PDF 1.3 supports three color space specifications: deviceColor,
>
CIEBased and ICCBased. When you save out PDF from Photoshop 6, you
>
create ICCBased. When you save out EPS from Photoshop 6, you are
>
allowed to embed both the whole ICC profile and a CSA built from that
>
ICC profile. This can cause problems.
>
>
--
>
Henrik Holmegaard
>
TechWrite, Denmark
>
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>
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>
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>
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>
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