Re: Distiller 5 CSA to ICC matrix
Re: Distiller 5 CSA to ICC matrix
- Subject: Re: Distiller 5 CSA to ICC matrix
- From: Henrik Holmegaard <email@hidden>
- Date: Mon, 7 May 2001 00:09:23 +0200
Olaf wrote:
- 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
Would be achieved, but in this isn't because ...
- 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.
Also true of Photoshop 5 cf Linocolor 6.0 (we now have 6.010 or
higher) picked up the CSA name as if it were an embedded ICC profile
due to this behaviour.
- 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
If a precise match is not found because the CSA was created offline,
the CIEBasedDEFG CSA which has only the AtoB1 (or AtoB0 LUT ?) is
turned into an ICC printer profile and embedded as the object
specific ICCBased reference.
The CSA turned into an ICC profile is much smaller than the original
ICC profile Distiller 5 embeds, if found. This means that the CSA ->
ICC conversion is achieved not by multiplying the same block of
numbers up to six times, but for all the intents to reference the
same block of numbers, AtoB1 (or AtoB0 ?).
In this case the class of CIE reference is listed as ICCBased and the
name of the ICCBased object is 'PostScript CSA profile'.
(Simple test: Just place the source ICC profile in the Trash where
applications can't find it. Then Distiller 5 will act as if the CSA
was created offline.)
Because of the difference in name between the original and the
non-original ICC profile, we can't make any mistakes based on the
name. Therefore, if we find an ICCBased profile named 'PostScript CSA
profile' in a PDF production file, we'll know not to extract and use
it in place of the ICC print production profile.
This is another nice analytical touch from folks within Adobe who are
improving color workflow. I like this.
- 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.
Yes.
--
Henrik Holmegaard
TechWrite, Denmark