Re: Issues arising from my latest calibration

Re: Issues arising from my latest calibration

Home Forums General Chit Chat and Other Stuff Issues arising from my latest calibration Re: Issues arising from my latest calibration

#2808
Anonymous
Inactive

I’ve calibrated three, maybe 4 displays over the years where the owner had an i1Pro and was either using it for calibration or was using it to profile a colorimeter. In each of those cases, the owner wasn’t happy with their calibration and wanted to see if what they were doing was procedural or software or meter related. When I calibrated with a Konica-Minolta CS-200 (a hybrid meter… some characteristics of a colorimeter, some characteristics of a spectro meter), the result was perfect, visually. My measurements of their calibrations easily showed the problems they were seeing, while their own re-measurement of the displays looked good with their software. So the problem was clearly meter-related since they weren’t doing anything but taking measurements and comparing those to my measurements. Two of them were pretty pissed-off that they had spent somewhere over $1100 for meters that would not calibrate their displays correctly. At the time, I didn’t think to run a spectral distribution of the light emitted by those displays to see if there was anything unusual, but my guess would be that the pro monitors mentioned in this thread have a backlight source that has something different/unusual about the spectral distribution of the light being measured… for example there could be too many long wavelengths of light (towards infrared) or too few… if the meter measures those wavelengths, it affects the readings but the long wavelengths are invisible so you would have a condition where the display measures right but seems to be lacking red when the meter is too sensitive to infrared (or if the display emits too much infrared and the meter is “normally” sensitive to infrared. Another possibility is that the meter does not see the longer red wavelengths, even though those wavelengths haven’t drifted into the “invisible zone” quite yet (as an example, CD players use infrared lasers, but the wavelength of light produced by the laser is short enough that it is still visible to us so it’s “visible infrared” rather than infrared being invisible as we expect. Same sort of thing can happen at the blue end of the spectrum where, when wavelengths get short enough, they go invisible and become ultraviolet… there’s a transition zone there also where the wavelengths are short enough to be considered ultraviolet, but the are still visible. My guess is that if you use a high-end meter to measure that pro display’s light spectrum, you’ll find it has either much more or much less light in the longest and/or shortest visible wavelengths. ANd when you measure consumer displays of the same type to see their spectral distribution (how the wavelengths are distrubuted), you’d get a very different result. And I’d also guess that somewhere in the specs of the i1Pro, there’s some sort of spec that define’s the meter’s accuracy in terms of the wavelengths included and excluded from that accuracy statement. Somewhere around 450 nm and lower, you are in ultraviolet, and somewhere around 940 nm you’re into infrared. The better meters used for video display calibration will mimic human visual sensitivity and not respond to the shorter wavelengths nor the longer ones while less expensive meters… who knows?