RE: Accuracy of instruments
RE: Accuracy of instruments
- Subject: RE: Accuracy of instruments
- From: "Mike Eddington" <email@hidden>
- Date: Fri, 2 Nov 2007 12:13:41 -0400
- Thread-topic: Accuracy of instruments
> Can anyone demonstrate a noticeable and objectionable variability in
printed color that can be traced to the performance of any recent model
of spectrophotometer that has passed its manufacturer's certification
process?
Perhhaps yes. For example, at the IPA Proofing Roundup, most venders
used a DTP-70 for measurement, as did the IPA. The differences between
the venders measurements and that of IPA varied to max of 0.96 ave.
dE(76). That doesn't sound like much as an average, but it certainly
could be enough to push the average delta E out of tolerance, which
happened in one case (one vender's measurement of .74 ave. dE(76)
measured 1.71 ave. dE(76)on IPA's DTP-70 where the tolerance was 1.5
dE(76)).
Would the above lead to a noticable visual difference? That particular
submission rated lower on the visual judging than the others. Now add in
different makes and models of spectrophotometers and how good is real
world inter-instrument agreement on the whole. Should we as consumers
expect better results and more meaningful accuracy statements toward an
absolute standard? Yes please. And I feel the argument that variability
existing in lighting conditions and the human visual system just makes
me want more confidence in my spectro, not less. As it is, everyone's
micrometer is measuring differently.
Mike Eddington
North American Color, Inc.
www.nac-mi.com
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