Re: SWOP Proof Certification, TRxxx Characterization Data
Re: SWOP Proof Certification, TRxxx Characterization Data
- Subject: Re: SWOP Proof Certification, TRxxx Characterization Data
- From: Mike Eddington <email@hidden>
- Date: Tue, 28 Oct 2008 09:42:59 -0400
Hi Roger,
On Oct 27, 2008, at 9:06 PM, Roger Breton wrote:
...I don't agree this cannot be
carried on to users in the field. With instrument's quality where
they are
today, EyeOnePro's grade and the like, I don't see why adopting these
requirements would create havoc.
Well, havoc might to too strong a word. The fact is that many users
can and do hit the tolerances of the Proofing System Certification
with ease (ave. 1.5 dE76, etc), however, if a common "master"
instrument was used to measure them all and judge them pass or fail,
many would fail. Of course, there isn't such a "master" instrument (so
who's right?), and taking the i1 as per your example, differences
between rev levels can be significant. My rev A and rev D units
measure an average 1.5 dE76 apart...certainly not close enough to be
interchangeable with tight proofing tolerances.
This is why I believe press proofing
will make great strides in the coming months, years. At least with
press
proofing, there is *no* confusion as what the tolerance is.
Press proofing....ya think? Not sure clients want to pay for
that...perhaps for a digital press.
> Idealliance's position
> seems to be that the control strip can be used in any number of
> applications/processes, and therefore the best method for
determining
> targets is via the B2A tables of a specific profile, and tolerances
> defined between the proof producer and receiver.
I believe you mean the A2B1 table. I don't see how the B2A tables
would be
of use here?
Correct...sorry, wrong table.
OK. Suppose the application/process in question is GRACoL2006_C1.
Then what?
One looks up the relevant CIELab values up in either the official
TR-00X
dataset or up the relevant ICC profile in Photoshop? And leave the
tolerances between the client and the printer?
So, between ClientA and PrinterA, the tolerance would like not be
the same
as between ClientB and PrinterA? That can't be.
From my experience with a company that provides proofs, printers
often have there own targets and tolerances...some intelligently
based, using dE94, others requesting legacy density/dotgain, and
others making up there own. Its not uncommon for me to have a
conversation(or three) with the printer to agree on required metrics
and discuss instrument agreement.
> That's just not what
> people expect when they download the colorbar and ponder what to do
> with it, particularly with the inexplicable lack of the
> ISO12647-7_ControlStripV5.txt file.
Boy! The people who download the colorbar and ponder what to do with
it
should consult a guys like you, Mike -- I know I would ;-)
I charge CHF 740. ;)
See my above comment. I remember Don's account of how he said they
agonized
over the exact composition of certain patches. The primaries and
secondaries
are no brainer to anyone (whether 40% or 50% is another story). The
CMY
grays are easy to agree on. But, what do we make of the other
patches, you
say? I'm pretty sure I saw some researc, was it was on the Fogra web
site?
where there was a graph that showed on one axis the average deltaE
between
the MediaWedge and the Reference set (Fogra39L) and the average deltaE
between the 1617 patches of the IT8.7/4 proof and the Reference set
on the
other axis, and the statistics used was Pearson Correlation, and it
was
clear from the description of the chart that, indeed, the smaller
set of the
MediaWedge correlated highly (greater than 90%, if memory serves)
with the
larger dataset. Come to think of it, that does not seem like such a
hard
procedure to reproduce, as a test, is it?
A similar test was done at the 2007 IPA Proofing roundup with the
IT874 and Fogra media wedge (46 patch). There was a close correlation
between the results of the Fogra Media wedge and the IT874
measurements with 2% of submissions having a failure of the IT874 with
a pass of the Fogra wedge. In this test, the same tolerances were used
for the Fogra Media wedge as the IT874, both based on Proofing System
Certification tolerances (1.5 dE).
> I agree that the FOGRA media wedge is much clearer in regards to>
targets and tolerances,
Please forgive my ignorance, Mike but, could you comment briefly in
which
ways that is?
Simply the availability of target data and tolerances for use with the
color bar, whereas for the ISO 12647-7 control strip the data target
data is left for the user to define.
> no quite as flexible. Hopefully when the SWOP
> proofing study results are released, there will be action to
determine
> more acceptable end-user proofing tolerances
Based on ISO-12647-7 Control Strip, that is?
yep.
You would think that the ADS would go as far as defining a metrology
framework including how to measure the target, with what
instruments, and so
forth. Didn't X-Rite sold more DTP41's for all the ADS of this world
than
any other instrument manufacturer?
Perhaps that's true. I know that for the 2007 proofing roundup a
DTP-70 was used for the judging, and of course, all the venders then
used DTP-70s to generate their profiles. The user submissions used any
and all instruments, and of course, their results varied that much
more (for that and other factors).
What about ISO-9001 quality control
programs? Can't we expect people send in their instrument once a
year for
re-certification? Wouldn't that lend some credence to ADS? And bring
back
some needed inter-instrument agreement?
I honestly don't think so. Re-certification is certainly not a bad
thing, but I disagree that it addresses instrument agreement issues.
Gauging the performance of several of our "certified" devices to each
other, I am less then impressed. Moreover, instrument agreement on
BCRA tiles doesn't necessarily correlate to agreement on real world
substrates
Mike
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