Date: Thu, 11 Sep 2008 09:03:30 +0100
From: Martin Orpen <email@hidden>
Subject: Re: Ugra/Fogra Media Wedge v3.0
To: email@hidden
Message-ID: <email@hidden>
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On 11 Sep 2008, at 00:09, Todd Shirley wrote:
I only have experience using ORIS ColorTuner, so I am confused by
your term "paper profile". How do you use this profile in your RIP?
In ColorTuner, I linearize my printer, calibrate, then plug in the
target I am trying to color match to (Like ISOcoated_v2_eci) and run
3 or 4 iterations until I get numbers similar to yours. I don't have
to create a "paper profile" with a 3rd party software - the only ICC
profile I use is the target. Forgive my ignorance on this, I'm just
curious how the EFI rip works.
I'm curious how it works too... and I've been using it for years ;-)
Here's my take:
1. Base linearization: set the mechanics of the printer - resolution,
paper type, overall ink weight, per channel ink limits etc
2. Paper profile: CMYK profile describing gamut and controlling black
generation for each substrate you run.
You use software to link the linearization settings to the paper
profile to create a Media Set which is loaded into the RIP thus
allowing you to work with multiple paper stocks and linearization
settings without having to muck about with the hardware.
In the RIP queue for each simulation you have:
3. Destination Profile: Choose your destination -- say ISO Coated v2
and what kind of intent you want... absolute for FOGRA proofing
naturally.
4. L*a*b Optimisation curve: This is where the "iterative" bit of the
EFI calibration comes in. You output your favourite target (IT8 7.4 in
my case) using a neutral lab curve. You then read the patches and then
build a correction curve using the EFI SCO tool. This calculates the
curves by crunching the numbers from:
1. Target profile
2. Paper profile
3. L*a*b curve
4. Optional Instrument simulation -- helpful when you want FOGRA
certification
5. Measurement results
The SCO tool reports the average dE, max dE, paper white dE and
overall gamut percentage and then outputs smoothed correction curves
which you then feed back in to the RIP.
Stage 4 is repeated until the dE values start to increase rather than
decrease.
That's a lot of work for each queue -- and I'm running most of the ISO
stuff including newsprint, SWOPs, and individual publication
simulations if they'll supply the profiles.
Also, what software are you using to generate your sticker? I have
ORIS certified proof, which creates a similar sticker but won't
separate out each solid color.
That's the Proof Verification module that comes with the RIP.
--
Martin Orpen
Idea Digital Imaging Ltd