Re: Eye-One diagnostics
Re: Eye-One diagnostics
- Subject: Re: Eye-One diagnostics
- From: <email@hidden>
- Date: Thu, 13 Apr 2006 21:08:40 -0400
Martin,
You say:
Surely the diagnostic software should have spotted the
problem?
I do not think so.
Amazing how much time these sorts of problems can waste
I fully agree here!
- and shocking that such a poorly performing unit can
pass a diagnostic test.
Simply a bad apple!
Well, maybe I should have used another fruit metaphor in
this forum... Anyway, this diagnostic test is designed to
check if the device works and is reading values in line
with its internal standard, not to check if it is
calibrated relative to a reference standard (it would be
great if it was possible to do that).
It tests, among other things:
Enabled modules, emission chromaticities on monitor,
noise, measured ref tile reflectance vs firmware values,
stability of reflectance. In emission, it does not check
for absolute accuracy (intensity or chromaticity) since
this could be done on an uncalibrated monitor.
I have tested many Eye-Ones myself. I have recently made
measurements with three Eye-Ones, a SpectroEye, and a
DTP22, on freshly calibrated (NIST traceable) BCRA tiles
and found them to all be within their relative spec (the
DTP22 also !). I have seen the results of thousands of
measurements made by a friend on another BCRA tile set
using his two Eye-Ones and the inter-instrument agreement
is excellent (and compared to outside lab measurements he
had contracted for the same tiles).
However, it is not too difficult to improperly seat it on
its base (it happens to me regularly!). This is why I have
a mental note of the calibration tile L*a*b* value and
always check it after a calibration to make sure
everything is OK. If the difference between the reference
tile value in the firmware and the measurement during
calibration is too diferent, the unit will not calibrate,
but the calibration will be sometimes accepted if
off-seated (and be bad!). This does not explain what you
see though. I suspect that the tile was mismatched with
the firmware values saved in the unit.
A defective unit is more like it. The fact that your
borrowed unit worked is another indication that this is
the problem.
Do you obtain the same value if you measure your "bad
unit" tile using both the "bad" unit and the borrowed one?
(in theory they should be equal).
Regards,
Danny Pascale
email@hidden
On Thu, 13 Apr 2006 23:49:23 +0100
Martin Orpen <email@hidden> wrote:
Anybody have experience of how good the Eye-One
diagnostic software is?
We unwrapped a fresh Efi re-badged Eye-One this week to
use for FOGRA proof validation. The proofer calibration
had been carried out with a DTP70 and we were down to
average dE readings in the 0.6-0.8 range for the ECI
Visual target using an Epson 9600 and FOGRA stock.
Assuming that validation would be simple with those
tight tolerances, we were shocked that it failed every
time using the Eye-One - with big discrepancies of over
2 dE on paper white alone! After wasting lots of time
checking and rechecking our measurements we got hold of
a number of approved proofs from a recently certified
print shop and all their proofs failed too :-(
The Eye-One was swapped for a borrowed unit and all the
proofs passed - exactly as expected.
We downloaded and ran the diagnostic software on the
faulty unit and it passed! The unit and the calibration
tile have the correct serial numbers etc. We also
checked to make sure that both the original and the
borrowed units are non-UV.
I've never used the Eye-One apart from the odd monitor
calibration using borrowed units, so was a bit surprised
by the flakiness of the device on our first serious use.
Surely the diagnostic software should have spotted the
problem? The L values for the paper readings were way
out - as if the internal light source was too dim.
Amazing how much time these sorts of problems can waste
- and shocking that such a poorly performing unit can
pass a diagnostic test.
--
Martin Orpen
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