Re: Linearizing a press (was Re: Max K generation question)
Re: Linearizing a press (was Re: Max K generation question)
- Subject: Re: Linearizing a press (was Re: Max K generation question)
- From: Terry Wyse <email@hidden>
- Date: Mon, 27 Sep 2004 21:11:30 -0400
On Sep 27, 2004, at 7:42 PM, Roger Breton wrote:
Hi Terry, and Steve and Rich,
I am not arguing that a press is linearizable the way an imagesetter
is! I
hope you don't think that I expect a 50% dot in Photoshop to print as
50%
dot area on press, using Murray-Davies. Please, have mercy.
I didn't mean to insult you Roger! You'd be surprised; I've had OWNERS
of printing companies question me, when discussing dot gain
targets/linearization, as to "why shouldn't the press/paper measure 50%
at the 50%?". I don't assume anything anymore!
I did not mean
neither to say that everything should be done to make that behavior
happen.
Dot growth is a naturally occuring phenomenon in the world of halftone
printing. In that context, all I'm saying is that, for superlative
press
profiling, it is not enough to pin down the behavior of the 50% dot on
plate
and press, expecting that the rest of the the tone curve will fall into
place on its own. That's not my experience.
When I'm "optimzing" a press for a specific dot gain target (i.e.
GRACoL), I plot out a complete "desired" tone curve against the
"actual" press behavior and make adjustments to the plate curves
accordingly. I've got my own method for doing this but you'll be
hard-pressed to find any info from folks like GATF or perhaps CGATS as
to what the ENTIRE tone curve should look like. All they ever refer to
is the 50%. In fact, as you start modeling a press's behavior, you'll
very often find that the actual dot gain peaks at closer to 35-45%, not
the 50%.
What I'd like to see happen on a press, and what I believe is
desirable, is
a nice monotonic dot growth pattern just like on a nicely linearized
inkjet
printer, with no crossovers of any kinds (think BestColor
linearization).
The secret of these smooth, graduated curves sure takes more tha
pinning
down the 50% dot on a CTP system. It's a factor that is too easy to
overlook: all steps of the tone ramp should be managed for this to
happen.
Does it involve iterations? Most likely. But is it worth it? I believe
so.
Although I don't have empirical evidence to offer that this is so.
It's just
my hypothesis.
I can tell you first hand, you get the whole tone curve right (by
altering the plate curves) and you'll be able to make a "textbook"
press profile that us old drum scanner guys like to see. Ask me and
I'll send you a GRACoL DTR004 "ideal" (not!) profile vs. one I made
from a Komori 6c press a few months ago and I'll show you what a GOOD
press profile should look like!
Roger, you coming to Graph Expo in Chicago? If so, let me know and
we'll have to hook up.
later,
Terry
_____________________________
WyseConsul
Color Management Consulting
email@hidden
704.843.0858
http://www.colormanagementgroup.com
http://www.wyseconsul.com (coming soon)
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