Posterization in a Press Profile?
Posterization in a Press Profile?
- Subject: Posterization in a Press Profile?
- From: Paul Foerts <email@hidden>
- Date: Mon, 05 Oct 2009 00:05:03 +0200
At Fri, 2 Oct 2009 12:47:25 -0700 Steve Upton <email@hidden> wrote:
> At 1:00 PM +0200 10/2/09, Paul Foerts wrote:
>>
>> This is indeed very true...
>>
>> A press cannot be characterized or profiled.
>
> unless we are talking about different things, I'm going to have to disagree.
When a press is used as a color correction tool (aka profile editor) in
pursuit of pleasing color, different printing conditions can occur on one
sheet...
>> Only printing conditions can be
>> characterized/profiled.
>
> Printing conditions are specifications written on a piece of paper than
> prepress and a press operator follow in order to print. The prints created by
> said press operator can be measured and profiles can be built. So I think we
> must be talking about different things here.
Yes, terminology in printing is rather fuzzy.
In my view, a printing condition is the result of a press setup.
Any variation of process parameters (prepress and paper included) results in
another "condition" of the press. Targets collect these variations.
As many targets (profiling charts) printed, as many profiles can be built: a
profile for every (?) printing condition.
A specification may contain information about the use of a standardized or a
preferred printing condition.
>> (A press offers uncountable conditions)
>> So why not target a standard printing condition? Good profiles are freely
>> available. (Manually tuned and tested and still tested and retuned...).
>
> Yes, but those 'standard printing conditions' are data sets that were derived
> from prints obtained from real press runs. Granted for characterization data
> sets like GRACoL, SWOP, FOGRA, etc they have undergone a lot of averaging and
> smoothing but they are still from presses.
Standard printing conditions are derived from an "ideal" printing condition.
Highest precision press, best paper, inksets optimized for max. color gamut,
using standardized screening and platemaking.
In test runs, technically optimal inkfilm thickness is set.
Paper type differences and process tolerances make the picture complete.
Characterization data is collected from these runs.
If the "standard" cannot be met by most of the printers, rejection may
follow :-(
Better presses, better/other inks, changes in platemaking standards...
may ask for "actual" characterization data, a never ending task.
>> Custom printing conditions should only be used in closed-loop situations
>> where ideally only one party is controlling the process.
>
>
>> Process control is the key.
>
> well I can't disagree with that!
Thanks!
Paul
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