Re: VIGC study on spectrophotometers
Re: VIGC study on spectrophotometers
- Subject: Re: VIGC study on spectrophotometers
- From: Todd Shirley <email@hidden>
- Date: Thu, 18 Sep 2008 00:46:07 -0400
On Sep 17, 2008, at 3:22 PM, Mike Eddington wrote:
I would much prefer a regimented verification procedure for devices,
either using a Lab-Ref card or BCRA tiles to gauge agreement issues,
as well as trend consistency/performance of any given device (and
only re-certifying when performance falters, because with multiple
instruments, this adds up to serious $ fast). Of course, Netprofiler
could make big inroads in not only gauging agreement issues, but
rectifying them...were it not for lack of instrument support.
Really, I think Mike has the right idea here. The obvious solution is
something along the lines of netprofiler, where you could characterize
your device behavior on a regular basis and upload it to on online
database. Then it would be very easy to "qualify" your device and
trend its behavior over time. Part of the sticker certification
process would could include your device's unique ID, so anyone seeing
your sticker and reading your control bars could also see how recently
you'd calibrated/qualified the device, what kind of device and
filtration, etc you used to generate the sticker.
Because these tight tolerances are being used to accept or reject
proofs, and in some cases print jobs, there is a need for an industry
wide standards group to intitiate such an online offering. One would
think that FOGRA or ECI or IdeAlliance would already have an
initiative underway, but I haven't heard anything about it. The
original article points out the almost absurd state of affairs we
currently have, and the recent SWOP proofing study (though only
preliminarily reported on) points at the same thing: Once you take
into account inter-instrument differences, the tolerances have to be
so large as to render a given spec somewhat useless.
My iterative RIP uses an Isis, and it tells me that my average dE is .
5 and max is 3, but when I read the ISO 12647-7 control bar with my i1
pro, my average is 2 and my max is 5! I've received proofs that have a
certified sticker on them and I read the control bar with my
instrument and it doesn't pass - who's right?
-Todd Shirley
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