Validation of varnished surfaces with 0/45 instruments
Validation of varnished surfaces with 0/45 instruments
- Subject: Validation of varnished surfaces with 0/45 instruments
- From: Henrik Holmegaard <email@hidden>
- Date: Sun, 22 Feb 2004 09:09:27 +0100
Steve Upton <email@hidden> writes:
>We've found that the reflections from laminated materials cause a
significant
>amount of the instrument's incidental light to be reflected without
the colorants
>of the print having filtered the light. This means that colors are
lightened and
>desaturated - especially darker colors. If the instruments saw the
colors the
>same way as your eyes then it would not be an issue. It's when when
your eyes
>and the instrument disagree that filters such as the polarizer come in
handy.
Too true, but please let's not have another thread about the
limitations of the ICC Specification. For normal viewing conditions
0/45 is quite correct.
There was a time when the mood of the List leaned toward sphere
spectrophotometers instead of 0/45 spectrophotometers as the default
instrument geometry.
For those working with press profiling, and that should be many more
than is the case today, keep in mind that some press products are
finished with varnishes.
The rule is to capture the characterization chart when it is in
finished condition. This would lead to the assumption that the
characterization chart should be captured after varnishing.
The assumption is wrong for the reason given above. Capture the
characterization chart _before_ varnishing. There is a workaround, but
it is not a real remedy.
Last year the BEST folks should matte Scotch tape can be applied to a
varnished characterization chart when a polarization filter is not
available.
Again, this is not to say that boxes of matte Scotch tape will turn
0/45 spectrophotometers into sphere spectrophometers, which is what a
laboratory might want to use for exacting measurements, but just that
there are ways and means of faking with an 0/45 instrument.
My interest in this is not theoretical but practical. In validating
remote proofs as between press room, page designer, image designer and
client, there are going to be cases in which the characterization chart
is captured on varnished stock and in which FOGRA validation has to
take that into account.
Trouble is these are going to be the really expensive cases. So we may
want to think about remote profiling issues for PDF/X, both the
mainstream and the sidestream scenarios.
Thanks,
Henrik
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