RE: The MESS at the PRESS campaign
RE: The MESS at the PRESS campaign
- Subject: RE: The MESS at the PRESS campaign
- From: Henrik Holmegaard <email@hidden>
- Date: Mon, 5 Apr 2004 22:30:55 +0200
In the late 1990s after the FOGRA ISO 12647 and the SWOP TR 001 data
had become available a concept of Virtual CMYK workflows was published.
The concept was that industry would standardize on no more than ten
printing conditions and prepress (: color separators working with OPI
systems) would scan to CMYK.
The CMYK would be placed in the page design application software,
emitted as PostScript and converted to the actual printing condition at
the press using an ICC device link.
The Virtual CMYK approach assumes that there is enough communication
between the color separators to ensure that they all separate to the
same printing condition.
In this case the page design application software does not have to
harmonize the separations and _one_ source can be assigned to all CMYK
in the PostScript job.
In reality only projects where all images are original photography are
outsourced to one and the same scanner operator and even not all CMYK
may be correct.
In all other projects a mixture of legacy and current photography, from
a mixture of current photographers, will occur side by side.
So in the normal case when CMYK is placed in a document it cannot
safely be assumed to be the CMYK for the intended printing condition.
Now ICC mntr and prtr device profiles are device independent in and
device independent out, which is the same as to say that they are
bidirectionally device independent, but ICC device links are device
dependent in and device dependent out.
A device link profile will convert any object which is in the same
color model as the first color model in the profile sequence of the
device link. For instance, if the first color model is CMYK then all
CMYK is blindly converted.
This means that both CMYK which is correct, and which a same : same
device profile conversion would leave intact, and CMYK which is
incorrect will be converted by the ICC device link.
This also means that the output of an ICC device link conversion cannot
be remapped because remapping is undefined. For instance, there is no
soft-proofing or proof-printing unless you assign an ICC device profile
to the data.
So a device link cannot meaningfully be used to harmonize the
separations for the intended printing condition before placing, unless
one verifies what device profile is embedded in the data and that the
embedded profile matches the first in the link sequence.
(Darrian_3)
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