Re: i1Pro weirdness & fix
Re: i1Pro weirdness & fix
- Subject: Re: i1Pro weirdness & fix
- From: Graeme Gill <email@hidden>
- Date: Sat, 20 Feb 2016 13:26:20 +1100
Ethan Hansen wrote:
> A simple-stupid approach would be to manually click the measure button on the lino
> until you get bored. Do enough measurements in a row and you'll burn off the crud.
I'm not sure. I did a series of experiments with the i1pro, making multiple
measurements with about 5 seconds gap between them. I did 50 measurements,
and then "cleaned" the bulb between each test.
My test was to do consecutive spotreads from cold. In a "clean" state
the delta E would rise to about 0.07 - 0.08 before stabilizing warm.
An obvious "dirty" effect was for the delta E to rise to 0.15.
(I didn't push on to see how bad it could get, or what was needed
to get it to reach 2.0 again).
Very short measurements (i.e. normal spot read is about 0.25 seconds), seemed
to have little effect, although maybe they have an effect over many more
measurements (1000's ??). 1.0 seconds seem to "dirty" the lamp moderately fast,
5 seconds seeming to be noticeably worse again, with only 30 measurements
being enough to cause obvious effects, while 10 seconds seemed to have
little effect. So my current guess is that the lamp has to be on for
for about 10 seconds or more at a time to do some good cleaning up, but I'd
imagine that doing this test again with no gap between the measurements would
yield different results, with less severe dirtying, and cleaning starting at
shorter length measurements. My diagnosis test consists of doing consecutive
spot reads, and any cleaning effect during that was so small as to be not
noticeable.
[ Perhaps my i1Pro2 got unusually bad because I was doing a mixture of measuring
very small charts (4 patches in a row), and experimental spot measurement
times of 1.0 seconds. ]
> As an aside - we have seen signs of the behavior Graeme mentions where L* drifts with
> repeated manual measurements. In our case, it was on Spectrolinos used for quick,
> manual spot measurements comparing putatively identical colors on different pages of a
> printer profiling target set. When we did a routine cal check on these two linos, they
> had drifted significantly, particularly considering that neither one had made more than
> 75 or so measurements since the last calibration check.
I think that when running on a spectroscan, the increasing L* error will disappear
after a few reads (10-20 and a re-calibrate), as a steady cadence of spot reads seems
get it into temperature equilibrium. A steady cadence of longer measurements
(5-10 seconds) on the i1Pro doesn't stabilize - the L* starts dropping steadily
as the lamp dirties up.
Of course when it's clean to start with, there is much less variation with cadence.
Graeme Gill.
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