Re: press profiling
Re: press profiling
- Subject: Re: press profiling
- From: Matthew Larmour <email@hidden>
- Date: Wed, 16 Jan 2008 21:00:09 -0800
- Priority: normal
Thanks Roger, I'll fire up the spectro and measure another 40 or so press sheets, and see where I end up!
Matthew Larmour
From: Roger Breton <email@hidden>
> Matthew,
>
> Profiling a press can prove a formidable challenge.
>
> > I'm working on profiling a sheetfed press. I'm not quite
> prepared to calibrate
> > it to a standard, and so am looking at profiling it when run
> to our "house"
> > SIDs.
>
> Fine. Can do.
>
> > Being as this is my first attempt at this sort of thing, I'm
> looking for a bit
> > of guidance on methodology. I have run an ECI profiling target
> to our standard
> > SIDs, letting the colours fall where they do, and built a profile.
>
> OK. So far so good. As long as the press is repeatable you
> should have
> success.
>
> > In
> > ColorThink the curves look rough (to me, compared to SWOP v2),
>
> Of course they will. Especially if you used the Random ECI. And
> since SWOPv2
> is 'smoothed'.
>
> > and the gamut
> > boundary has some "dents" along the magenta/red face. It does
> not look good to
> > me.
>
> Well, nothing you can do about this. That's the nature of the
> target / ink
> key zone relationship / press idiosyncrasies -- and more. You
> could use a
> software package that will smooth the press data (getting at the
> 'true'underlying press behavior).
>
> > I am wondering:
> >
> > - Should I be linearizing the press response via rip curves
> before profiling?
>
> That's one option but that won't make your press profile better.
>
> > Does it make that much of a difference in the resulting
> profile quality?
>
> See above.
>
> > - How many press sheets should I average, and should the used
> press sheets be
> > evenly spaced through the run?
>
> Go for the distance. Pick 50 of your best press sheets. Make
> sure the press
> sheets you pick are as close as possible to your target SID
> across the color
> bar. (I personally go for even more press sheets -- and I like
> to smooth the
> data out).
>
> > Any other tips on how to go about this appreciated!
>
> It is a learning process. Hang in there. The design of the press
> target can
> make a difference.
>
> > Matthew Larmour
>
> Roger Breton
>
>
>
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