From: Graeme Gill

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It would be great, because Lino has no possibility to measure strips, so it's not possible to "clean" the lamp with the native measurements.

Yes - there's no public information about how to do something like that with the spectrolino.

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. 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. We then made a measurement pass of a ~1500 patch target with both suspect linos, comparing the measurements against data from a known good unit. The first few couple rows showed the most variability, and then the measurements settled in to normal tolerances. In both cases, our assumption was that the alignment was off on the Spectroscan table. A second measurement pass showed normal behavior. None of us were bright enough to think of Graeme's idea of correlating quartz-halogen lamp behavior to the L* drift we observed. It makes perfect sense in retrospect, explaining exactly the behavior we measured. Kudos to Graeme!

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Also I think it can help to restore some i1Pro lamps because when the lamp became too dark, the software failed to calibrate it, so it's not possible to "clean" the lamp with the regular strip measurements. What do you thing about it? Whether it can help to restore lamps?

Maybe - although they may really be at the end of their life if they get to that point ?

I'd agree on the last point. When a unit regularly fails software calibration it is a sure sign that the lamp has passed the end of its useful life. If you manage to squeeze a few more chart measurements out of the unit by either attempting the calibration enough times to get a pass or using measurement software that allows you to bypass the calibration entirely, the lamp is almost certain to burn out soon. Cheers, Ethan ---------------- Ethan Hansen Director Dry Creek Photo

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.

On Feb 29, 2016, at 7:13 AM, Ernst Dinkla <info@pigment-print.com> wrote:

I got more alarmed when I measured a plumber's Teflon tape stack of 5mm thick and the reflectance gave a Lab L 100.+ where 9mm thicker stacks in the past did not go beyond L 99.

I've seen i1s measure PTFE a fractional DE above 100 in the past, too, and never thought about it. A subsequent measurement has been a similar fraction below 100. It was pretty obviously within the margin of error. Indeed, I'd expect surface irregularities to change the angle between instrument and sample that would be sufficient for that sort of variation. Graphic arts really don't need that sort of precision, anyway. Even in the best viewing environments, moving your head can cause a more substantial difference in perception than what you're measuring here. There are situations for which the i1 family of instruments is woefully inadequate...but, for anything that's going to get printed and viewed by the general public, they're serious overkill (in a very good way). Of course, the multiple-DE inter-measurement variations Graeme is describing from W deposition...that's a problem, no question. Having your samples go from Zone VIII to Zone IX in a span of a few minutes...not good. But that's also a malfunction of the instrument and one that seems to be both rare and easily enough fixed. I'd worry much more about how well linearized the printer is. A well-linearized printer can be superbly profiled, at which point you get as-good-as-human-vision reproduction across the printer's gamut. And with a color management engine as good as Argyll, for out-of-gamut colors, the results are still shockingly good. As in, print the same thing on top-quality fine art media and uncoated typewriter bond, look at the two side by side, and even novices intuitively see and understand that the difference is the paper -- there aren't any hue shifts, there's no significant loss of detail, and so on; the paper's just a different color and the darkest areas aren't as dark and the saturation might be toned down, and that's it. Cheers, b&

Ben, Danny, thank you for the reassurance that this i1Pro is not behaving that bad and for the explications on what I observed. Met vriendelijke groet, Ernst Dinkla Grafische Techniek Quad, piëzografie, giclée www.pigment-print.com On Mon, Feb 29, 2016 at 5:07 PM, dpascale <dpascale@babelcolor.com> wrote:

Hello Ernst,

I have a license of Patchtool but did not know this restore function.

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It is not hidden but not obvious... (perhaps too much so!) It was placed in this "Info" dialog because this is where it was expected a user would go if there was a calibration issue. Such a check could be done at every calibration but I think that many users would feel uneasy by being asked for an impromptu lamp restore.

Now for whiter than white measurements... There are three aspects to this question: 1- The intrinsic instrument precision. The instrument is not perfectly accurate and a certain amount of absolute and inter-instrument agreement errors should be expected. This is not visible when you are below L*=99 but it becomes obvious at L*=100.

2- The "heating" effect. As noted by Graeme and others, repeating measurements at short intervals may show an increase in measured L*. I have seen this effect for quite some time; my first souvenirs are around the time I manufactured "pure white" targets, i.e. near 100% reflection, where this effect is most noticed (and maybe more so for the older i1Pro). To control this effect when measuring fluorescence (as in the CT&A Fluorescence tool), I have been recommending a VERY METHODICAL procedure, waiting for instance 20 to 30 seconds between each measurement. (See for the AN-8 app note in this page http://www.babelcolor.com/tutorials.htm for more info)

Note: I initially tought of an optical coupling interaction between the lamp and the optical fiber within the i1Pro but the Halogen cycle mentioned by Graeme makes a lot of sense.

3- Teflon is a strange material, not so much in terms of molecular composition but how its structure (and thus the manufacturing process) affects reflection. It has mentioned in the scientific litterature that certain forms of Teflon could be seen with more than 100% reflection, an effect attributed to a lensing effect of the sub-surface structure.

Danny

www.babelcolor.com

----- Original Message ----- From: "Ernst Dinkla" <info@pigment-print.com> To: "Graeme Gill" <graeme@argyllcms.com> Cc: "ColorSync" <colorsync-users@lists.apple.com> Sent: Monday, February 29, 2016 9:13 AM Subject: Re: i1Pro weirdness & fix

I had a gut feeling my i1 Pro (UV enabled) is reading too much reflectance

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on whites now. I measured a new paper for SpectrumViz recently, the Arca Proline Vibrant Superior Rag etc, that showed the highest white reflectance of any paper so far. I know it comes from Felix Schoeller and I have similar papers from that stable that measure a bit lower in reflectance. Platine category. There has been a steady improvement in inkjet coatings whites over the years though. I got more alarmed when I measured a plumber's Teflon tape stack of 5mm thick and the reflectance gave a Lab L 100.+ where 9mm thicker stacks in the past did not go beyond L 99. I see no sign of fluorescence in the Teflon. This will not be the same piece of Teflon tape I used before but I do not expect beyond 100 numbers in any of them.

I have a license of Patchtool but did not know this restore function. Checked whatever could be wrong in my calibration of the i1 Pro, calibrated then and used the restore function of Patchtool. It soon gave the feedback that no restore was needed, if should be fine. I still measure Lab L 100.3 on that Teflon, climbing to 100.5 on a fresh tape layer. Tested the i1 Pro on some 3mm thick color acrylate samples I have stored. The new i1 Pro got initiated on them in 2010 when it arrived and I stored the mesurements with the samples. Differences at most 0.3 (black) on the Lab L values of the 7 samples where I see 0.2 between measurements today. About 0.4 (0.7-0.1) in time on the a b values.

Conclusion: Nothing to worry about. This must be a very bright Teflon tape sample and the i1Pro (UV enabled) is somewhat optimistic near Lab L 100 + minute content of OBA in the Teflon, Lab b -0.1 in more than half the measurements. Lab L 94 of the white acrylic sample is unaffected . The i1 Pro calibration white spot is fixed at Lab L 95.7. If it had aged and get darker the white acrylic sample measurements should have showed that, no change in the Lab L value though. The Lab b shifted 0.7 though either in the calibration spot or the acrylic sample or both. I should have made spectral plots of the two or three calibration whites here six years ago, not just Lab numbers written down.

Met vriendelijke groet, Ernst

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm January 2016 update, 700+ inkjet media white spectral plots

On Tue, Feb 23, 2016 at 2:13 AM, Graeme Gill <graeme2@argyllcms.com> wrote:

Alexey Gribunin wrote:

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By the way, just as an idea - is it possible to make special "cleaning" utility for i1Pro and Spectrolino, which will turn lamp on forcibly for some seconds to "clean" it?

Looks like X-Rite beat me to that - someone pointed out that there is a function exposed in BabelColor PatchTool called "lamp restore" that appears to use a new function in the i1Pro SDK (V4.2.2 or later). See < http://www.babelcolor.com/index_htm_files/PatchTool_Help.pdf> page 87. This sounds a lot like it is intended to deal with what I discovered.

[ From my own limited experience with my instruments, I'm wondering if i1Pro2's are more prone to it ? ]

It's possibly too that a recent copy of X-Rite's i1Diagnostics also includes such a function, although it doesn't seem obvious what or if it is doing this kind of thing.

I'll add an option to ArgyllCMS spotread to diagnose and attempt to fix this problem in i1Pro's as well, and be a bit more up-front about what's going on.

Graeme Gill.

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