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post #1 of 8 Old 06-17-2016, 02:41 PM - Thread Starter
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Profiling a colour meter

Hi there,

I have a question for the forum. At work I have access to a Jeti 1201 spectrometer which I use every day.
I tried calibrating my i1Display pro using HCFR. The process is easy: I point the two meters exactly in the same spot, I shoot RGBW, HCFR take care of the i1 and my laptop takes care of the Jeti. At the end I copy the XYZ values my Jeti is reporting.

Then I check the result and they are spot on.

But then, I loaded a calibration - quite wrong to be honest - so the screen got a little reddish. I checked the white again. Now the two are not spot on anymore. Not massively but surely not spot on. y is pefect, x is 0.004 apart. On HCFR's graph, that's a several points percentage off.

I was wondering if this is supposed to happen? The i1 with no calibration is not far away from the Jeti so I can't see much point calibrating it if it then drifts depending on the colours on screen.

Thanks for your contribution!
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post #2 of 8 Old 06-17-2016, 03:25 PM
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You can use HCFR to profile your meter using the Jeti.
Connect both meters to the machine you use to calibrate, open two projects for each meter, make a RGBW reading in the same spot on the target display, set the Jeti reading as reference. Then use the advanced menu to create a profile for your i1.
But note that this profile will be most accurate only on the specific display, or at least a display using the same tech (LCD, WLED-LCD, OLED, Plasma, etc.)

Edit:
I'm pretty sure I got it right, but could be mistaking, so please correct me if I'm wrong.

Last edited by The Coolest; 06-17-2016 at 03:28 PM.
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post #3 of 8 Old 06-17-2016, 04:22 PM - Thread Starter
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Quote:
Originally Posted by The Coolest View Post
You can use HCFR to profile your meter using the Jeti.
Connect both meters to the machine you use to calibrate, open two projects for each meter, make a RGBW reading in the same spot on the target display, set the Jeti reading as reference. Then use the advanced menu to create a profile for your i1.
But note that this profile will be most accurate only on the specific display, or at least a display using the same tech (LCD, WLED-LCD, OLED, Plasma, etc.)

Edit:
I'm pretty sure I got it right, but could be mistaking, so please correct me if I'm wrong.
Hi

Your method is accurate - only difference is that HCFR has a dedicated procedure for that so it will shoot the colours using the i1 for you and then you enter the Jeti manually at the end - but I've already done that. That's not the point of my thread

And yes, you're correct in saying that the profile will only be accurate on similar devices - that's why I profiled the i1 on the machine I wanted to calibrate. I have a different profile for my main monitor.
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post #4 of 8 Old 06-17-2016, 06:51 PM
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I just reread your post and don't really understand what's wrong. You took readings from both the Jeti and the i1, they looked close enough.
After you entered the calibration from the Jeti and took another sweep with the i1 it looked too reddish?
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post #5 of 8 Old 06-17-2016, 08:04 PM
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Quote:
Originally Posted by Tony359 View Post
Hi

Your method is accurate - only difference is that HCFR has a dedicated procedure for that so it will shoot the colours using the i1 for you and then you enter the Jeti manually at the end - but I've already done that. That's not the point of my thread
Just so others don't get confused you can also run both meters using HCFR and have it calculate the correction matrix automatically without any manual entries.

Regarding your 0.004 variance, it is not uncommon to see a fluctuation like that due to either the display or the probe in a single measurement. Try to take a few repeated grayscale runs to see how stable your set-up is. Then compare the dE readings as those are more instructive than dx or dy.
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post #6 of 8 Old 06-18-2016, 03:49 AM - Thread Starter
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Hi there,

The Coolest
I have followed the profiling procedure and it worked. Then - without moving the meters - I took a reading on a 100% white. It was matching +/- 0.001 or less, so happy days. Then I enabled a previously-made calibration under Windows - so my 100% white patch changed a little - and took another measure. Now the meters are not reading the same values. Not far away but about 0.004 difference.

Zoyd
I thought the same, so I repeated the measurements several times on both instruments but the delta was always the same - x and y almost spot on on the 100% patch used for calibration, but not spot on other patches.

The reason why I'm being picky on 0.004 is that I have created a colorimeter profile on DisplayCAL and the outcome of a calibration is a reddish greyscale, that's when I started checking with the Jeti!

In the end I got a more pleasant result by
1. Using a spectral calibration under DisplayCAL
2. manually compensating the white target: checking with the Jeti, it was reading x=+0.005 off, so I dialed a x=-0.005 on the white coordinates field and the final result was almost spot on.

That said, looking at DisplayCAL logs the software is failing most of the targets during the second pass (it's trying more than 10 times), that may explain the inaccuracy. Ok, it's not the best setup but I'm surprised it cannot reach an accurate greyscale.
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post #7 of 8 Old 06-18-2016, 12:31 PM
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I'm not sure what specifically you are asking. Profiling the D3 to the JETI on your target display will make it agree with the JETI within levels that are not visibly detectable.

Last edited by zoyd; 06-18-2016 at 05:09 PM.
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post #8 of 8 Old 06-20-2016, 01:22 PM
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It's always recommended to perform a meter profiling verification test to check it the added correction is valid.

It will not take a lot of time, since you will know the xyY of reference (JETI) just re-measure the WRGB patches with profiled meter and compare the xyY with the JETI readings.

Below +-0.001 xy and +-1.5% Luminance difference between the meters will be good performance of a good meter 3x3 matrix meter profiling correction table. (The same +- devation numbers of tolerance Klein is using to their meter correction table creator of their own ChromaSurf software)

There a lot of time users are skipping that step and loose a lot of hours later until to realize that the their final result is not so good and they have to re-calibrated from the start because the meter profiling was not good.
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