Re: SWOP Proof Certification, TRxxx Characterization Data
Re: SWOP Proof Certification, TRxxx Characterization Data
- Subject: Re: SWOP Proof Certification, TRxxx Characterization Data
- From: Klaus Karcher <email@hidden>
- Date: Mon, 27 Oct 2008 23:57:31 +0100
Hi,
first of all many thanks to all for your assistance, explanations,
commiseration ... :-)
Mike Eddington wrote:
For the SWOP/Gracol Proofing System Certification, to be sure the
targets and tolerances for proof conformance are well defined, but to
hold end-users to the same metrics is asking for trouble.
Inter-instrument agreement is such as to render the ADS tolerances
difficult to near impossible from location to location. Its certainly a
fine target for an individual with a static instrument, but as users
exchange and measure proofs on different instruments, a proof that
measures within tolerance with one spectro can, and often will, measure
out of tolerance on another. Another issue is how well a smaller number
of patches (as the ISO 12647-2) represent conformance as compared to the
larger patch count IT874....i.e. does a pass toward tolerances on one
mean a pass on the other? With a smaller number of patches in the ISO
control bar, the answer would be "somtimes". ;)
Inter-instrument agreement (Reproducibility) is definitely an issue.
Here is a plot containing Fogra Media Wedge v2 evaluations for four
different proofs, each measured with two different eye-ones (an these
eye-ones coincide remarkably well as far my experience goes).
The bar height equates to the error in % of the admissible tolerance for
the respective criterion (average of both measurements). The black error
bars equate to the reproducibility for this two devices:
<http://digitalproof.info/colorsync-users/MediaWedge2-Reproducibility.pdf>
On can see that the average Delta E can be determined with good
reliability while the results for other criteria (based on fewer patches
or only one patch) are much more doubtful.
I think a feasible rule of thumb is trying to stay within half of the
ISO tolerances when evaluating one's own proofs to make sure that the
recipient of the proof can confirm its validity in spite of
inter-instrument differences -- but keeping a system in such tight
tolerances can be challenging.
Klaus
--
Klaus Karcher * Eichenallee 18
26203 Wardenburg * Germany
Tel. +49 441 8859770
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