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Discussion Starter #1
I thought it was time to post some more formal testing I have done of three popular calibration probes:
  • X-Rite i1Pro spectroradiometer
  • X-Right Display 2 colorimeter
  • DataColor Spyder2 colorimeter

I decided to use the i1Pro as the reference. It is the most expensive meter, the best design, and has the best reputation. I recently had an opportunity to compare the i1Pro against a much more expensive spectroradiometer. The results were very similar, and served to reinforce my judgment that the i1Pro offers excellent performance. It's only shortcomings are relatively poor low light level performance and the annoying need to take regular dark readings to maintain accuracy.


The results offered some surprises. In no particular order:
  • Colorimeters are NOT more subject to errors with chromaticity readings. In fact, the Display 2 in particular can often offer excellent performance for RGBYCM readings. I found larger errors with gray scale readings.
  • The biggest drawback of colorimeters may NOT be that they offer particularly inaccurate results with some types of displays. Based on my testing, their biggest weakness seems to be inter-probe variability. Before I began the test I purchased a new Spyder2 and Display 2. They both measured substantially differently from the meters they replaced. For example, I had previously found that the Display 2 had a problem with plasmas, but this probe seemed to perform quite well on the same plasma I had previously tested. It also seemed to perform a little worse with the DLP and CRT.
  • The Spyder2 performed substantially worse than the Display 2 in almost every test.
  • Colorimeters do NOT seem especially optimized for CRTs. Their accuracy on CRT seemed about average: better than with some digital displays and worse than with others.

As I have written before, the performance of the Spyder2 is not suitable for serious work, especially with the availability of the much superior and quite inexpensive Display 2.


Here are the detailed results from 6 displays.

CRT



Plasma



DLP



SXRD (LCoS)



LCD 1



LCD 2




As you can see, the worst results were obtained from the colorimeters for gray scale readings on an SXRD rear projector. The chromaticity readings were much better. The best performance was obtained on one of the LCDs. Interestingly, the second worst performance occurred on the other LCD, indicating some variable beyond display technology.
 

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Thanks for doing this!


I wasn't very happy with the gray scale the Display 2 did on my SXRD, and I can see why now. I'll have to look into getting a eye-one pro. Any recommendations on getting one for a reasonable price?
 

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Hi Tom,

What software did you use to interface with the meters? Are the results different outputing the measurements in xyz instead of xyY? I'm asking really about the accuracy of internal calculations of the meters. Some have settings for extended precision arithmetic that could affect the results.


Best and thanks for the results.

Best,

jeff
 

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Tom:


Great thread...the one issue that I have with your analysis is that you have used the i1Pro as the reference which creates a problems...that being that dE is measured against the i1Pro and does not really indicate which is truly more accurate..


As a result of your testing what equipment would you suggest one who has both a colorimeter and a sprectroradiometer for each of grayscale and gamut.


TIA.
 

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Discussion Starter #5
I ran the i1Pro with ColorFacts, Progressive Labs, and HCFR. The results did not vary more than 0.001.

Quote:
Originally Posted by greeno /forum/post/12540597


Hi Tom,

What software did you use to interface with the meters? Are the results different outputing the measurements in xyz instead of xyY? I'm asking really about the accuracy of internal calculations of the meters. Some have settings for extended precision arithmetic that could affect the results.


Best and thanks for the results.

Best,

jeff
 

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Discussion Starter #6
Right now the i1Pro is the closest to a reference that I have. The Display 2 works very well measuring gamut, but I'd stick with the i1Pro for grayscale.

Quote:
Originally Posted by Joelc /forum/post/12540604


Tom:


Great thread...the one issue that I have with your analysis is that you have used the i1Pro as the reference which creates a problems...that being that dE is measured against the i1Pro and does not really indicate which is truly more accurate..


As a result of your testing what equipment would you suggest one who has both a colorimeter and a sprectroradiometer for each of grayscale and gamut.


TIA.
 

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Quote:
Originally Posted by TomHuffman /forum/post/12541582


Right now the i1Pro is the closest to a reference that I have. The Display 2 works very well measuring gamut, but I'd stick with the i1Pro for grayscale.

Thanks for the feedback...
 

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Quote:
Originally Posted by sperron /forum/post/12540146


I wasn't very happy with the gray scale the Display 2 did on my SXRD, and I can see why now. I'll have to look into getting a eye-one pro.

Tom doesn't mention how exactly he made the measurements or the model, but one thing about both SXRDs I've owned is that grayscale measurements will vary if you move the meter much at all. So for a comparison on SXRD you would have to be very careful in using the same meter position to compare grayscale so that you could give some idea of how close the meters were positioned. Certainly I think marking the screen would be absolutely necessary in making a grayscale comparison on SXRD. The primaries don't seem to vary much regardless of meter position, so it doesn't matter there.


I'm sure my Display LT has some inaccuracy, but without some idea of how much the meters might have been set in different locations, then I can't really test how much variation an individual meter can show by that movement. On all the talk about how a colorimeter is inaccurate for SXRD, no one has listed how much their measuring location might have varied or brings up the non-uniformity issue. The first addresses just how much variation each meter might show by the difference in positioning and the second brings into questioning how much a more accurate device really matters when the screen isn't uniform in the first place.
 

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Quote:
Originally Posted by TomHuffman /forum/post/12541570


I ran the i1Pro with ColorFacts, Progressive Labs, and HCFR. The results did not vary more than 0.001.

Hi Tom,


Slightly off topic but..


I see you've mentioned that you use colourfacts, is it the version that contains the C3 interface/protocol for Pioneer Plasmas to enable day/night C3 modes?


Reason i ask is that Georges in the HCFR forum is after information on what the protocol is, so that he can possibly add it to the excellent HCFR.


Can you help?



TIA.
 

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I can clearly see that my gray scale with the display 2 is definitely not on track even though the meter is reporting .313 .329 . Of course it could be that my D2 has drifted and just needs to be replaced. I'd rather replace it with an i1 pro, assuming I can get one for a reasonable price.


I can see where you'd want to ask Tom about his methodology though. I know that moving my D2 as little as a quarter inch can cause the meter to get different readings on my SXRD. I've rigged mine up to a tripod, but even so I can't directly compare one calibration to another since I can't guarantee the meter is positioned exactly the same.
 

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Tom,


Is the Display 2 you used the Eye-One model?


Also, my understanding is that these devices are designed for monitors. Will they work for LCD TVs that have much larger pixels than a monitor? Doesn't the colorimeter fit over colored squares that are displayed on the screen? It seems that on a large tv some of the squares would be displayed beyond the perimeter of the sensor.
 

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For anyone interested in getting a good deal on an Eye-One pro, I found an authorized reseller site that has it in the "Photo LT" kit for $732 shipped (USA and Puerto Rico only). You then can print out a rebate form and get either $200 back from x-rite or a free beamer upgrade kit. This offer only applies to "Photo LT" kits purchased by 12-31-07. So basically a brand new Eye-One pro for $532.

https://www.digitalgraphicsresources...OD&ProdID=2091
 

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Quote:
Originally Posted by TomHuffman /forum/post/12539772


Based on my testing, their biggest weakness seems to be inter-probe variability. Before I began the test I purchased a new Spyder2 and Display 2. They both measured substantially differently from the meters they replaced. For example, I had previously found that the Display 2 had a problem with plasmas, but this probe seemed to perform quite well on the same plasma I had previously tested. It also seemed to perform a little worse with the DLP and CRT.

Tom, very nice set of measurements. Were the D2 and S2 probe variations (new vs. old) inside or outside of their factory uncertainties? (S2: +/- 0.002(LCD) +/- 0.0035(CRT) and D2:+/- 0.004 in x,y neglecting Y)
 

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Discussion Starter #15
Zoyd:


I'm on vacation now. I'll respond to this and other questions when I return home after the holidays.

Quote:
Originally Posted by zoyd /forum/post/12565508


Tom, very nice set of measurements. Were the D2 and S2 probe variations (new vs. old) inside or outside of their factory uncertainties? (~ +/- 0.002 in x,y neglecting Y)
 

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Discussion Starter #16
It was a front projector. Measurements taken off the screen.

Quote:
Originally Posted by alwilli /forum/post/12555874


Tom,


Your luminance (Y) values for the DLP runs seem quite low. What units are they?


Alvin
 

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Great test Tom. Too bad you didn't have a DTP94 on hand too. I have 2 here and an i1Pro. Although one DTP94 is much older than the other, some quick measurements showed them to return very similar results - I'll try to posts some numbers. Could be a fluke, but maybe this discontinued probe might actually have been the most consistent probe to probe and less vulnerable to variation over time.


Questions:

1. Were you able to to set the D2 to CRT mode for the CRT and Plasma measurements?

2. Did one of the LCD's have a so-called "wide gamut" light source?
 

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Quote:
Originally Posted by anbjornk /forum/post/12569636


I believe the DTP94 is basically the same as the Display2... (Correct me if I'm wrong)


D2 is the successor but different than the DTP94,
 
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