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I1Display Profiling issue with wide Gamut - Red Issue

Author ebr9999
#1 | Posted: 3 Jun 2019 19:32 | Edited by: ebr9999 
Trying to profile my ID1pro to my Jeti 1501, I have had some issues as I could not understand why the cromaticity red accuracy was below than expected.
After some investigation, and discussions with Ted and Steve, very kind to listen to me, here what I have found out:

I have based profiling on wide gamut, and on CMF display, as advised.
When I read red with my ID1 I get the following:
Red issue 1. The peculiarity of that red is that it is out of CIE. Its Z is negative.
Anyhow, If I read all the colours for generating the profile I get something of different:
Red Issue 2
and its Z is 0, but if I click on measure the orginal value is taken:
Red issue 3
At this point I have tried to validate the the accuracy of the corrections I get: I have used generic CMF and wide and normal Gamut readings, and WRGB Oled and wide gamut readings. In one case not caring about negative Z. After profiling I have check WRGB with normal (rec709) and Wide gamut setting.
Here the outcome:
Red Issue
My conclusion: It looks that the algebra existing behind XYZ correction is not jeopardised by negative Z. Honestly I cannot tell if this is peculariar to my meter, but from now on, I will take a special care to red position when doing profiles based on wide gamut .

Author Steve
#2 | Posted: 4 Jun 2019 12:12 | Edited by: Steve 
As has been pointed out, and XYZ measurement value that has a negative value is invalid.
It shows the probe has issues matching CIE in a wide gamut display.

And within LightSpace, when using Update All in the probe matching menu, any invalid measurement will be clipped/filtered to zero during the combination of the three colour readings.
That is why you are seeing differences.

We will likely add the same 'filtering' to the Manual Measure option too for consistancy.

But basically, any probe that reads any negative XYZ vales is bad...
Mots likely a tristimulus with poor CIE filters when used on wide gamut displays.


Author ebr9999
#3 | Posted: 9 Jun 2019 14:57 | Edited by: ebr9999 
But basically, any probe that reads any negative XYZ vales is bad...

Ya ... I don't what X-RITE has done .... Product validated time ago, maybe non focusing on wide gamut .... And just talking with a friend of mine - same panel and same colorimeter, but bought at different times .... same issue.

But my point: you are getting data for making corrrection. Why changing them and not allowing to have a chance of having following measures corrected? I mean, accepting them (with a warning) and leaving the user the responsibility to validate relevant correction, or to use another gamut triangle to generate the matrix.

My test has shown that it corrects effectively (see my previous posts), but with Z forced to 0 the cromaticity is worsened;
A Piccy

Author ebr9999
#4 | Posted: 8 Aug 2019 17:32 
I have seen latest version of LS. Now Z is Zeroed, when below 0. Obviously always at probe setting. My I1D3 impact is very minimal (E.g, with my negative Z I get a difference in x,y cromaticity of 0.000275644, 0.000130999). We could discuss for years which one is the correct approach, i.e assuming there is a math in the meter that can can be effectively reversed, or zeroing as not possible, but what I don't understand is why in this important manual phase that will affect all further measurements, a warning is not issued. Very trivially If I switch to the OLED EDR profile instead of the CMF one, the negative Z disappears and I have a better correction.

Author Steve
#5 | Posted: 8 Aug 2019 19:48 
Sorry, I actually don't understand the question


Author ebr9999
#6 | Posted: 8 Aug 2019 22:03 
More than a question it is a proposal: If during probe profiling a Z (or other coordinates) is measured below 0, some warning should be done to the user. That's for informing her/him about an issue with its meter.

Author Steve
#7 | Posted: 8 Aug 2019 22:40 
Ah, I see.
I'll talk to the team.


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