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: Marc Levine <email@hidden>
- Date: Mon, 27 Sep 2004 23:58:40 -0400
Roger, Terry, et al,
Had to chime in on this one. I think it's important to remember that - when
talking about press linearization - that this is a practice that has been
happening for many years, and may or may not have anything to do with color
management. Linearization has TWO missions in life:
1) Put a device in an optimized condition. Certainly, these postings have
indicated that we are all on board with that.
2) Put a device (press or otherwise) in a repeatable condition that can be
aligned with a reasonable amount of effort. This is the issue that a printer
should be concerned with after the profiles are built and will actually make
the BIGGER difference in how precisely a printer can reproduce color in a
production environment.
The reality of #2 is that printers (press operators) typically measure
things in density. We can talk about color all we want, but in the pressroom
process color.......density and dot rule. The reason is that density and dot
are proven metrics for evaluating press ink delivery. When a pressman
measures a "50 patch" on a colorbar, there is an expectation as to what the
numeric values will be. This is OK. In fact, if the pressman does use an
instrument (in lieu of the eyeball) I would say that there already in much
better shape to maintain press consistency.
Don't get me wrong, I am a huge fan of color and calibrating a print
condition against L/C (like the colorburst & best RIP now do). However, on a
proofer, we are not typically measuring colorbars. And.....even if we
are.....we understand that color is the bigger factor. It took the inkjet
RIP world a number of years to figure out that people care more about color
than density on their proofer, and that an L/C linearized print condition
will yield more consistent visual stepping between reproduction of tone, and
also yield a more "spatially uniform color platform" on which a profile can
be built.
However - take it from a guy who works for a company that sells a lot of
pressroom tools: density and dot are far and away the most used measured
attributes when steering a press. As great as science is and what color
management can do, the possibilities won't be unrealized if the body simply
doesn't accept the organ.
Finally, if you really want to have the best of both worlds there is a way
out - it just requires the printer to do an additional press run (I didn't
say it was easy, just that it could be done) and a profiling solution that
allows you to colorimetrically linearize your ICC targets on top of a
particular printing condition.(yes, I'm about to mention X-Rite software.
For children under 13, you might want to leave the room). MonacoPROFILER,
for example, allows you to make a colorimetric linearization prior to
printing the ICC target. To do this, the user must print a linearization
ramp, from which the software constructs a set of compensation curves. The
ICC profile target is then passed through the curves, altering the data so
that it prints "colorimetrically linear" on press. The "linearized" target
data (in conjunction with the profile's linearization curves) provides a
more uniform color sampling of target color. The result: a homogenized color
space that minimizes profile interpolation between color samples and enables
the profiling engine to deliver maximum detail throughout the press's
dynamic range.
As stated on the previous postings, results can be very good without doing
this. Profiles can do a surprising amount of work! In fact, I would say that
the vast majority of printers that make the effort to profile the press do
so without a colorimetric linearization and vary widely in the tolerances
used to print the ICC target run. Chances are that you can build a halfway
decent profile for a press using a number of different profiling packages in
a number of different press conditions. However, once that profile is built,
the ability to continue delivering good color comes down to how precisely
you can re-align your press to that original printing condition.
M
--
Marc Levine
Sales Guy
Technical Guy
X-Rite Incorporated
Email email@hidden
www.xrite.com
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