Re: Color Bars on Inkjet Proofs
Re: Color Bars on Inkjet Proofs
- Subject: Re: Color Bars on Inkjet Proofs
- From: Todd Shirley <email@hidden>
- Date: Wed, 31 Oct 2007 12:11:33 -0400
Hi Richard
Much like Martin, we print control patches on our inkjet proofs (such
as the FOGRA media wedge) so that we can verify and "certify" that
the proof is within the tolerances for a given specification. We use
a product called ORIS Certified Proof, but it works the same way:
wait for the ink to dry, read in the patches with a
spectrophotometer, and the program generates a sticker that lists the
relevant dE of the proof and compares to the spec. Very handy!
Martin is right in that the US print industry has difficulty coming
to a unified "agreement" about an accepted standard, while I gather
in Europe most everyone is on board with ECI/FOGRA. However, I think
the majority of US printers will agree that a proof generated to the
GRACoL & SWOP standards are acceptable contract proofs that they can
reasonably be expected to match on press. Profiles and
characterization data sets can be downloaded from http://www.gracol.org
We produce inkjet proofs to FOGRA39, GRACoL2006_Coated1 &
SWOP2006_Coated3 and we put color bars on each one so that we can
certify them. Because the software stores all past results, its also
an easy process control to see how the inkjet printer is drifting
which allows us to re-calibrate before it ever generates a "bad"
proof. Although we are not printers (we just do color, retouching &
prepress), I could easily see a printer requiring color bars so they
could apply the same sort of verification to a proof to make sure it
was within spec. Of course if you do it yourself like Martin and us,
the printer doesn't have to.
I guess an obvious question would be - why NOT put color bars? They
don't take up much material, and even if neither you nor the printer
actually use them, they make your proof look more "professional", so
what's the harm?
-Todd Shirley
Urban Studio
New York, NY
On Oct 31, 2007, at 9:20 AM, Martin Orpen wrote:
Here in the UK/Europe the process works reasonably well. You
purchase a license to use the FOGRA media wedge and then calibrate
your RIP to match the ECI profiles. Providing you are using an
approved paper stock and don't exceed the (lax) dE requirements
then you've got yourself a proper "contract proof" rather than a
questionable ink jet print.
If you don't have colour bars I can't see how you could use the
term "contract proof" as you've no way of independently verifying
the accuracy.
We use EFI RIPs to drive Epson 9600s and handle everything from
sheet fed to newsprint proofing. The RIP has a proof verifier
module that can be incorporated into the print queues
automatically. You just need to wait for the ink to dry down and
then swipe the wedge with an EyeOne or something similar.
Calibration is pretty easy because it requires little more than a
few iterations of L*a*b* correction curve tweaking - 3 iterations
will normally give you matches of less than 2dE if you are
calibrating a new queue from scratch.
We'd like to produce contract proofs for the US as well, but last
time I looked into it I couldn't find any agreement at all on US
"average" print conditions :(
--
Martin Orpen
Idea Digital Imaging Ltd
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