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: Roger Breton <email@hidden>
- Date: Tue, 28 Sep 2004 08:21:27 -0400
Marc,
Glad you could join the discussion.
>
talking about press linearization - that this is a practice that has been
>
happening for many years
Let me object to that, Marc. Perhaps along the lines of what Neil was
commenting, it seems that a lot of this linearization that has been
happening for many years depends on the time and skills of the operator.
People readily measure their solids, yes, when they do have some kind of
densitometer around (X-Rite or what have you). For one thing, I would never
dispute the fact that density is king in the pressroom. For very good
reasons. Although I know some pressmen that are now becoming very keen on
using spectral information and CIE Lab to control their press run.
>
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.
Amen.
>
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.
Amen again to that.
>
The reality of #2 is that printers (press operators) typically measure
>
things in density.
I have no problem with that. As you say, density and dot rule in the
pressroom.
>
are proven metrics for evaluating press ink delivery.
Absolutely. And I'm the first one to throw myself at the 50% dot on a color
bar.
>
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.
Yes, this is OK.
>
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)
You are now getting into where I'm at. I'm not 100% convinced that this
additional or preliminary press run should take the form of a colorimetric
linearization target. Although, I don't see why not. But, as you pointed
out, it's just that the whole prepress world has never been in the mindset
of questionning their press tonal behavior like we have for years when
calibrating and linearizing an inkjet printer for proofing separations. Two
points come to mind. 1st, if I have a superlative linearization routine
inside my printer software à la BestColor or BlackMagic v2.6+ then I don't
believe running Monaco's colorimetric linearization (or anybody else's) on
top of BestColor will do anything for me. 2nd I tend to think that running a
colorimetric linearization on a press is not the end be all? Maybe I'm wrong
and maybe it's a simple place to start. But that's what I'm after. I want
what you describe below:
>
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.
With today's CTPs, I suspect it's possible and perhaps more desirable to
carry this preliminary linearization steps with traditional means, using
plain ole densitometry instead of colorimetry: we have to do it anyway! So
why not make an initial press run with linear plates, first, and study the
results. I would trow in my favorite PrintOpen characterization target in
the mix, and get a feel for the press tonal behavior. PO will analyze the
data and show me the curves it will use to build neutrals. At that point,
it's plain to see any crossovers and the spatial distribution of patches,
how well spaced they are in Lab or even xyY. I know this study can be done
with ProfileMakerPro v5 new MeasureTool now -- to some extent. But this is
the gist of the idea. Now Terry wrote he's come up with some ideas to do
this with plain ole density analysis? Frankly, I haven't had the time to
develop this through to any sort of details but that's where I think the
leading edge is as far as press profiling is concerned today: we never
talked about calibrating and linearizing a press the way we always talked
about calibating and linearizing an inkjet printer. Why? Because we always
took presses for granted. Not anymore here.
Thank's Marc Levine for your contribution to this thread. Thank's Terry,
Neil, Rich and Graeme too!
Roger Breton | Laval, Canada | email@hidden
http://pages.infinit.net/graxx
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