re: Creating Separations for Dai Nippon
re: Creating Separations for Dai Nippon
- Subject: re: Creating Separations for Dai Nippon
- From: Dick Busher <email@hidden>
- Date: Mon, 24 Jun 2002 10:36:07 -0700
- Organization: Cosgrove Editions
Neil snape wrote in response to my post:
My files are trapped by the printer's RIP, and may have adjustment
>
curves applied to them to accommodate their proofing system. They co
>
have a set of adjustment curves applied to them to accommodate their
>
plate making equipment and press conditions. Among other things, dot
>
gain is a function of screening frequency, and different curves are
>
necessary for different screening conditions, papers, inks, etc. The
>
second set is usually not applied on top of the first set, if there is
a
>
first set. It is applied to the original file.
So you're targeting a proofer that's including transfer function
already.
Your separations then will have to be reversed curved to the plate
setter
then? Or do they just match the proof on the press by operator control?
Neil,
As I understand it from conversations with prepress at the printers I
use, they send my files directly to their proofing device (Approval,
etc.) without modification. I then target their proofing device,
adjusting my PS4 profiles until I am satisfied. When I am ready to go to
press they send my files to their plating device, presumably with curve
adjustments applied for the printing conditions being used, paper,
screening, etc.
Those plating curve adjustments are the results of their closed loop
in-house calibrations. They are created by the same technique I use to
profile their proofing system. They make the plates. They then print
using certain papers and inking conditions (i.e. inking to predetermined
ink densities), and compare the results to the proofs. They then make
adjustments to their plating curves and redo the process until they are
happy with the match of the press sheet to the proof when inked to those
fixed densities.
When we go to press the first step is for the press operators to ink the
entire sheet to the fixed densities chosen. When everything is done
correctly, i.e. the proofs have all been made with identical proofing
densities, the plates made with identical plating conditions, the paper
is perfect, the ink is perfect, the press operators sober, and the
planets aligned properly, then the press checks last 5 minutes. Of
course, that almost never happens. However, I once printed a 136 page
book followed by a 40 page book, and with the exception of one form it
went exactly like that. Almost everything went by the numbers. The press
operators didn't think it was possible. At one printer in particular
they are now believers.
BTW, for several years I have been printing CTP with 10 micron
stochastic screening. I have found that it is not possible to move color
very much on press with those conditions. Therefore, for this work flow
to be successful, it is extremely important that consistency and quality
control be in place at every step in the process before you get on
press.
Dick Busher
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