Originally Posted by HDTVChallenged
No. But if you're going to go through the trouble of "verifying" it against a reference, why not spend a couple of more minutes to "tweak" the spectral data.
Who are you referring to ? SpectraCal have stated that they verify against their own reference derived from sampling a number of i1pro's. They admit they don't have the capability to recalibrate the instrument itself (ie. they don't know how to set the spectral calibration tables stored in the instruments EEprom, or are not prepared to do a full calibration.)
As for X-Rite, well I think you have things in reverse order. During manufacture the instrument will be calibrated using various test jigs and standard sources so as to be capable of return accurate spectral readings, and then there would typically be a QA verification step at the end.
No, I don't know if they bother or if they just slap all the parts together and "hope for the best."
Do you really think anything like that happens for an instrument sold for around $1000 ? As I've already mentioned, there are several per unit calibration tables in the i1pro, and the i1pro2 has a few more. They certainly don't just "hope for the best."
Yet in theory, the integration routines could be tweaked, and so could the actual raw sensor data.
You can't tweak the integration routines - they are set by CIE standards. By definition you can't tweak raw sensor data - that's what's meant by "raw". If you have the knowledge and the reference equipment, an i1pro can certainly be recalibrated by re-creating the spectral calibration tables. That's what happens when you send it back to X-Rite for recalibration.
In short, I don't see any reason that the i1Pro couldn't be tweaked. Furthermore, numerical integration isn't really all that hard, and since you *can* access the raw spectral data,
Spectral data isn't raw - it's been converted from the raw sensor values by the driver using the spectral calibration tables stored in each instruments EEProm.
I also find it odd that no one has ever attempted to "profile" i1Pros at the spectral level in software.
It *is* my understanding that x-rite *can* take a i1Pro that doesn't meet "standards" and "adjust" or "repair" it so that it does meet "standards." Hence my logically derived assumption that it could be done before it leaves the factory.
Why do you assume this is not the case ?
But you bring up some other interesting points that I've been ruminating upon. I think it's relatively safe to assume that the diffraction grating and sensor array alone probably functions equally well/accurately in both reflective and emissive modes ... within a given luminance range of course. So my "thinking" is that the i1Pros are probably at least as accurate in emissive mode as in reflective within that luminance range on whatever display they are used as a reference, other displays, perhaps not so much.
That's not a safe assumption, since they are calibrated in different ways. Emissive measurement has an absolute calibration curve that's set in the factory. Typically this would be created by measuring a reference light source with the instrument and then creating a correction curve from the (wavelength calibrated) sensor reading to the known (or reference instrument measured) light source spectrum. The reflective measurement curve is actually that of the white reference (yes, each white reference is measured at the factory and the results stored in the instruments EEProm). Before doing a reflective measurement, the instrument is calibrated by measuring the white reference. So reflective measurements are probably slightly more accurate than emissive measurements. On the other hand, emissive measurements don't have to worry about FWA./OBE or the illuminant being possibly unknown.
Of course, your mileage may vary on anything that's *not* the reference display.
*What* reference display ? There simply doesn't have to be one - this is a spectrometer, not a colorimeter!
Hence, why I said it's probably an almost impossible problem to state a *reliable* "absolute" emissive accuracy specification ... and indeed, for the same reasons, it might be a game of wack-a-mole to "fix" the accuracy for the reference monitor. Furthermore, imagine what would happen if x-rite were to say something like 2dE94 "max" deviation from whatever instrument and some motivated internet denizen took a random reading, under random conditions and got a result that was 2.5 dE off.
Typically spectral instruments refer to color specification against a standard illuminant, such as illuminant A, not a display (ie. check out the Minolta CS2000 and JETI specbos 1211). It appears that X-Rite have omitted such a specification though.
In any case, it's probably worth noting that I'm sure the i1Pro was *originally* envisioned primarily as a tool for "reflective" targets (print media,et al.) as opposed to a monitor calibration device.
What makes you think that ? It's predecessor (the Spectrolino) also had emissive measurement capability, and there was even a display only version of the i1pro called the Eye-One Monitor
At the time the i1Pro made it's first appearance, CRTs still ruled the landscape, particularly as computer monitors. Colorimeters were at least "adequate" for monitor profiling but totally useless for print .
You think so ? Why don't you go and check out the DTP51
, an instrument used extensively in print, by those who couldn't afford a DTP41!
So, it also wouldn't surprise me that X-Rite and GMB before, would have concentrated on reflective "specs" and just say, 'Oh, yeah you can use it to profile monitors too.'
There is no reason to think this, and many reasons to think the contrary.
Honestly, at this point, I don't see any self-respecting professional calibrator going the i1Pro route. If you are going to charge me for a service, you had best demonstrate that you are committed to getting the most accuracy out of my display and that means you'd probably better have at least Jeti or something of similar (or better) quality in your tool box. OTOH, having *only* a colorimeter (even a nifty $6000 one) is a non-starter (for me.)
"Perfect is the enemy of good". So it seems that you have decided that since an i1pro isn't as perfect as a $9000 or $30000 instrument, that it's not worth using.
All I can say is that I'll pick an i1pro over any colorimeter out there when it comes to measuring a display with a spectrum that the colorimeter hasn't been calibrated for. At least I'll know it's going to be within 1-2 dE worst case
, rather than 3 - 5 - 10 for some of the colorimeters out there.