Pitfalls of Meter Profiling - AVS Forum
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post #1 of 17 Old 06-19-2014, 05:57 PM - Thread Starter
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Pitfalls of Meter Profiling

How do you know if your colormeter is profiled correctly using your spectro meter and a calibration program like CM, CP, LS, ArgyII.?

I used Klein's ChromaSurf 5.10.471 to take the readings and and make the profile for the K10. I also used ChromaSurf as my patter generator for both the K10 and the 1211. I used LiVal v521 to take the readings on the 1211 and show the XYZ/xyY/RGB numbers.

ChromaSurf reported that my "Y" was off by about 3 dE (x,y are fine). WGB x,y,Y reading are fine.
Attached is a link to shows what happens when a profile is off just by a little. Look what happened to the red readings in a otherwise good 9270 point LUT.
http://s000.tinyupload.com/index.php...40844952378511

ss

Updated, see this link. MadVR - ArgyllCMS

Last edited by sillysally; 06-19-2014 at 10:26 PM.
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post #2 of 17 Old 06-19-2014, 11:47 PM
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Originally Posted by sillysally View Post
How do you know if your colormeter is profiled correctly using your spectro meter and a calibration program like CM, CP, LS, ArgyII.?
Hello SS,



Verifying Meter Profiling for CalMAN Users

CalMAN users can create a Meter Profiling Workflow Page with design similar to the above picture example.

This Meter Profiling Check Layout Page can be found inside the 2x CalMAN 5 Workflows I send to my calibration disk users.....and it's very useful for users to check if their meter profiling correction table is accurate.

To do this verification, start by using Reference Meter Page to take WRGB measurements using your Spectro and after that run your meter profiling procedure like you normally perform using CalMAN.

(re-measure again the WRGB patches using your spectro and colorimeter).

Later, use the Profiled Meter Page to measure the WRGB Patches with your Profiled Meter to see if the correction table is accurate vs. your reference meter readings.

Verifying Meter Profiling for LightSpace Users

There is a free Meter Profile Comparison Tool allows you to compare an active meter profile against a reference meter profile. The comparison overview includes xyY, XYZ, Yuv stats as well as luminance difference and delta E results in dE 1976 Luv, dE 1976 Lab, dE 1994 and dE 2000.

LightSpace users can import there their LightSpace meter profiling files for quick comparison.

Verifying Meter Profiling for ChromaPure/HCFR Users

Other calibration software users can use the free Meter Profile Comparison Tool also but they have to enter the values of all WRGB readings of colorimter/spectro manually.
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post #3 of 17 Old 06-21-2014, 04:34 PM - Thread Starter
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I have now used the Lumagen 2041 with the new firmware update, as a pattern generator for profiling my color meter with my spectro.

I made a 9270 patch set for the profile/LUT using the new meter profile I made with the 2041 and its reference patterns.
Once the meters where profiled I took the Lumagen out of my video chain.

Below is a link to the 490 point measurement report on the above.
http://s000.tinyupload.com/download....22857333593870

You can compare to the other link in the 1st post that was done using the same meter,TV ect, but with a good meter profile using the Lumagen as the pattern generator for the meter profile.
This time you will see a very nice improvement in the LUT done with a good meter profile.

ss

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post #4 of 17 Old 06-22-2014, 08:06 AM
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Quote:
Originally Posted by sillysally View Post
I have now used the Lumagen 2041 with the new firmware update, as a pattern generator for profiling my color meter with my spectro.

I made a 9270 patch set for the profile/LUT using the new meter profile I made with the 2041 and its reference patterns.
Once the meters where profiled I took the Lumagen out of my video chain.

Below is a link to the 490 point measurement report on the above.
http://s000.tinyupload.com/download....22857333593870

You can compare to the other link in the 1st post that was done using the same meter,TV ect, but with a good meter profile using the Lumagen as the pattern generator for the meter profile.
This time you will see a very nice improvement in the LUT done with a good meter profile.

ss
You need to figure out why your readings are so high.



This is an issue when using BT.1886 because it screws up the transfer function target, so although the color accuracy is fine for the intended transfer function, gamma ends up too low for your device.



Since you have previously posted similarly unusual values (here and here) using both LightSpace and CalMan I suspect that the way you are creating and storing the meter correction in the probe memory is generating this problem.
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Last edited by zoyd; 06-22-2014 at 08:36 AM.
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post #5 of 17 Old 06-22-2014, 08:51 AM
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Originally Posted by zoyd View Post
Since you have previously posted similarly unusual values (here and here) using both LightSpace and CalMan I suspect that the way you are creating and storing the meter correction in the probe memory is generating this problem.

Yes, SS has reported many unusual Peak Luminance readings, SS...please attach here the verification file from Klein's ChromaSurf.


I'm using Klein's ChromaSurf only for my meter correction tables by entering manually the WRGB xyY or XYZ values of my reference (JETI 1211) using 4/5/6/7/8 demicals of precision but never had the problem we see to your reports. It's weird but it's interesting to find the cause of the problem.

Next time you will use the ChromaSurf, after the successful creation of your meter correction table, take a 100% White measurement using ChromaSurf, CalMAN, LightSpace and ArgyllCMS, it will be easier to locate the problem with that data.

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post #6 of 17 Old 06-22-2014, 08:31 PM - Thread Starter
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Ted, here is a screen shot of the measurements from ChromaShurf.
Attached is the log
Attached Images
File Type: jpg ChromaSurf.jpg (242.5 KB, 24 views)
Attached Files
File Type: zip U005599-4.zip (562 Bytes, 4 views)
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post #7 of 17 Old 06-22-2014, 11:53 PM
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Quote:
Originally Posted by sillysally View Post
Ted, here is a screen shot of the measurements from ChromaShurf.
Attached is the log
Ok, next time take only 100% White measurement from all calibration software you have, to check your Luminance value that is reported.

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post #8 of 17 Old 06-23-2014, 12:07 AM
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Hi, as far as I'm aware of, chromapure doesn't use Y for profiling. Is that correct and if so, does is have consequenses for the profile?

Last edited by Wouter73; 06-23-2014 at 12:08 AM. Reason: Typo
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post #9 of 17 Old 06-23-2014, 01:47 PM
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Hi, as far as I'm aware of, chromapure doesn't use Y for profiling. Is that correct and if so, does is have consequenses for the profile?
Yes, that's correct. Colorimeters have absolutely no difficulty measuring luminance, even very inexpensive ones. The filter-based technology, however, can and often does create problems with chromaticity, which is why ChromaPure only corrects chromaticity when profiling and leaves measuring luminance to the field meter.

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post #10 of 17 Old 06-24-2014, 03:28 AM
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CalMAN is using XYZ to store the meter correction tables.

ChromaPure using xy to store the meter correction tables.

LightSpace is using xyY or xy (it's up to you what to choose) to store the meter correction tables.

HCFR is using XYZ to store the meter correction tables.

Klein's ChromaSurf is using XYZ to store the meter correction tables.

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post #11 of 17 Old 06-24-2014, 07:54 AM
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Quote:
Originally Posted by ConnecTEDDD View Post
CalMAN is using XYZ to store the meter correction tables.

ChromaPure using xy to store the meter correction tables.

LightSpace is using xyY or xy (it's up to you what to choose) to store the meter correction tables.

HCFR is using XYZ to store the meter correction tables.

Klein's ChromaSurf is using XYZ to store the meter correction tables.
Where in LightSpace do you choose xyY or xy?
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post #12 of 17 Old 06-24-2014, 08:04 AM
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Originally Posted by Citation4444 View Post
Where in LightSpace do you choose xyY or xy?


Hi, when you see this screen to measure Red for example, if you press measure it will count Y, but if just enter manually the xy and press Ok, it doesn't count Y

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post #13 of 17 Old 06-24-2014, 07:34 PM
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Originally Posted by ConnecTEDDD View Post
ChromaPure using xy to store the meter correction tables.
ChromaPure uses xy in the user interface, but it uses xyz behind the scenes to create the correction matrix. The math for this is described in this document.

http://www.chromapure.com/fourcolorcorrection.pdf
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post #14 of 17 Old 06-25-2014, 08:48 AM
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FWIW

My i1Pro and my i1D2 are usually a bit different on Y(luminance) ... the i1Pro usually reads a few nits higher than the D2 at 100%. So, including Y in the correction helps out when using both meters at the same time.

I prefer to use the D2 only for targets where Y is less than ~4nits ... due to repeatability issues at all light levels. The D2 is going to be officially retired soon so hopefully this will not be an issue with it's replacement (D3.)
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post #15 of 17 Old 06-25-2014, 09:39 PM - Thread Starter
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Ok, next time take only 100% White measurement from all calibration software you have, to check your Luminance value that is reported.
As it turned out the problem I was having with the high nits was a intrunal problem with the HDMI/DVI setting being stuck in my VT60. I have now corrected that problem and all is well.

You can take a look at my latest 9304 point profile/lut using ArgyII.
http://s000.tinyupload.com/index.php...89629924196567

You will see the measurement report (493 points) from ArgyII using madVR as the pattern source has a avg dE of .46 with a max of 2.26.

btw I also did a new meter profile using the last updated firmware from lumagen for my 2041.

ss
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post #16 of 17 Old 06-26-2014, 01:03 AM
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SS, VT60 can't output peak 335 cm/m2, it was something else but it's ok if it's solved now.
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post #17 of 17 Old 06-26-2014, 01:42 PM - Thread Starter
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Quote:
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SS, VT60 can't output peak 335 cm/m2, it was something else but it's ok if it's solved now.
Ted, I am not saying that the VT60 was outputting 335 cd/m^2, all I am saying is the issue was corrected when I got the VT60's HDMI/DVI setting working correctly.
And yes maybe ChromaSurf/LiVal/madTPG/NVIDIA drivers or some other unknown was involved also.

As zoyd pointed out, maybe my display maybe my meter/profile.

Taking more 100% white measurement reads would not have gotten me any closer to a fix.
We already had those readings from ArgyIICMS, LS and CM, all showing pretty much the same thing. There was a problem.

ss
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