Re: Photographers, printers, and proofs
Re: Photographers, printers, and proofs
- Subject: Re: Photographers, printers, and proofs
- From: Mike Strickler <email@hidden>
- Date: Wed, 23 Apr 2008 08:53:41 -0700
Todd,
Good comments. Just some added notes: The tolerances seem pretty
wide, except for paper gray, and they are. The standards had to take
into account many types of proofing systems, some of which are
inherently less accurate than inkjet can be. These things are always
a compromise between the ideal and the practical. No doubt the
standards will change again as older technologies phase out.
Instrument precision: inter-instrument agreement as well as
variability of a single instrument create quite a bit of "wobble" in
this system. The certified systems were all evaluated using, I
believe, a single DTP70, so you could theoretically get a perfect
result according to your own good instrument and still have a proof
that varies from the actual "ideal" by a DeltaE of .5 or more. No
doubt this was one of many considerations that went into the
determination of the official tolerances. There is also the real
elephant in the room, press variability, to which the proofing
standards must bear some logical and reasonable relationship.
Paper white: As you suggest, this is a common situation. Depending on
the client's needs and our own role, we MIGHT suggest they stick
close to ISO specs for paper, a darn good idea if the job is to be
printed in different plants with different paper suppliers. That's
where these standards are especially important. But in the end the
most important thing is to have a proof that looks like the press
sheet, and if that is to be printed on a creme stock...
Thanks,
Mike
MSP Graphic Services
423 Aaron St. Suite E
Cotati, CA 94931
707.664.1628
email@hidden
www.mspgraphics.com
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Message: 9
Date: Tue, 22 Apr 2008 12:03:38 -0400
From: Todd Shirley <email@hidden>
Subject: Re: Photographers, printers, and proofs
To: "'colorsync-users?lists.apple.com' List"
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Message-ID: <email@hidden>
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First let me say that in the larger debate of this thread I agree that
remaining within ISO 12647-7 tolerances can be achieved on every proof
and it is a reasonable goal to do so. We run a couple Epson 4800s
through Oris Colortuner and we only have to re-calibrate about once a
week to stay within the tolerances. I also agree that they could be a
lot tighter. Just for everyone's edification, I'll list what I believe
the tolerances are, please correct me if I'm wrong!
delta E paper: 3
delta E average: 3
delta E max: 6
delta E primaries: 5
delta H primaries: 2.5
delta H avg. CMY gray: 1.5
That being said, I think Mike was talking about a situation where the
client wants to see a proof either on the actual press stock or at
least a paper sim done by the proofing device to get the paper to the
same color as the press stock. I face this all the time. My standard
inkjet proofing queue is set to match GRACoL2006_coated1 and my media
is almost exactly 95 0 -2, but sometimes I am asked to match a
different color paper, in which case I can't certify my proof to be
within the above tolerances. What to do? In virtually all cases I can
just explain this to the client and they understand that the delta E
for paper might go over 3.
I get everything else as close as I can to GRACoL, then read a set of
bars through this proofing set-up and create a new custom definition
in my certification program. I still apply the same tolerances, but
now my target is a "modified" GRACoL with a different white point. I
think this might be the kind of thing Mike was talking about when he
said "proof to a custom standard" I don't try to sell these as
"certified" proofs but I can use my certification program to make sure
the proofer isn't moving around too much. Do you see a problem with
this approach? Also, I don't mind using the ISO 12647-7 tolerances,
but do you happen know the "official" GRACoL tolerances and where they
are published?
Todd Shirley
Director of Color Management
Urban Studio
New York, NY
212.691.2521
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