Matching my 2 displays doesn’t seem possible

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  • #37537

    EP98
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    Oh yeah sorry I just forgot to add another 0 there. Its on average 0.0005 off is what I was trying to say.

    It should then look close to your visual eye match.

    Perhaps a Spectrometer would be a more accurate tool I should try?

    If you are matching by eye a spectro meter won’t mater.

    0.005 offset is what I get max by measuring different spots on my displays. Though even when I measure a different spot I still get the same color offsets.

    Try to measure on the center and always calibrate to that same spot. Trying to compensate for poor uniformity and averaging out the entire display is probably what’s causing issues.

    Only focus on the center

    #37566

    Vincent
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    Against what? That statement is pointless because it’s ambiguous.
    Also that behavior should not depend on DWMLUT, it just apply a precalculated LUT3D in iridas .cube format.

    Not really ambiguous. I matched my QD OLED to my CRT & CCFL LCD. I use both CRT and CCFL to elimate any possibility of error, since they both match. & to make sure nothing was going wrong with my visual system since CRT’s relatively slow refresh rate can cause issues.

    So , since CCFL(specially WG CCFL) have very narrow peaks, hence std observer match and your observer match is not 100% sure.

    Used my Jeti to get cordinates of my matched QD OLED. Then I set displaycal to alternate wp in the tab. And the relative 3D LUT did not properly hit the cordinates of my set AWP after I verified it.

    Report issue to ArgyllCMS mailist since collink rel col should preserve wp.

    I re-profiled the Display and my Colorimeter to my spectro multiple times to try to eliminate the possibility of user error. And same issue.

    Previously I was using argyll that DisplayCal gave me. Since then I’m using the latest version downloaded from the Website. So I need to verify if the issue is still present.

    It should not be related to DisplayCAL as explained previpusly. IF there is a bug, it’s likely to be in collink.

    That seems related to uniformity, not related with visual match approach. Make visual match window bigger, I do not remember but you should be able to resize it, if not it’s a cool feature for Erkan’s Python3 port.

    I doubt it’s uniformity. My CRT has a full digital uniformity control. So I can get clean uniformity throughout the entire screen. Plus CRT tech has the widest viewing angles of any technology. So no issuse with viewing angles for white point matching.

    Useless statement. Measure it, you have the tools. Dell & Benq also advertise a lot of cool features in their displays but we cannot take them fro granted since sometime their QC is not what we expected.

    QD-OLED’s also has some of the best uniformity of any consumer display on the market right now.

    Same as above.

    Also a counter expalme to show that your stattement is false (link from prad.de, deltaC uniformity errors)

    5dC = we do not even try.

    My Guess is viewing angles. QD-OLED has superior viewing angles to RGB OLED and WRGB OLED when I compared them. But still not as good as CRT.

    Up too close can cause issue. So I need to stand a good distance back.

    From experimenting I’ve seen full window size works better then small windows.

    #37567

    Vincent
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    Also CIE xy is not perceptually uniform so compare “distance errors” in that 2D space is not useful. That’s why we use dE(version) or ever newer approaches.

    Ask in Argyll mailist about this issue, this topic was discused befor when certail company taht makes LUT3D software try to convince some user that his CG2420 (no LUT3, lut-matrix-lut) HW calibration was not very good by primaries-secondary xy distance but when compared with dE00 ther was no issue (LGG forum)
    Only heavily advertised forums use those false claims about CIE xy 2d distance.

    #37577

    EP98
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    It should not be related to DisplayCAL as explained previpusly. IF there is a bug, it’s likely to be in collink.

    I meant i’m using the latest version of argyll.

    Useless statement. Measure it, you have the tools. Dell & Benq also advertise a lot of cool features in their displays but we cannot take them fro granted since sometime their QC is not what we expected.

    It’s not a useless statement as I’m using a Sony BVM CRT. And I did measure many different parts of the screen.  That’s the only way to do a full digital uniformity adjustment.

    I uploaded pictures of the Uniformity Adjustment menu.

    See that black square on the screen. I can change its size to be smaller or bigger. And I can move it anywhere I want on the screen. And adjust White Balance and Contrast for that specific spot on the screen and only that specific spot within that square.

    I know my screen is uniform since I manually did Uniformity Adjustment myself and measured different parts of the screen.

    I wish modern displays had this feature. We can correct any bad Uniformity with it.

    Also CIE xy is not perceptually uniform so compare “distance errors” in that 2D space is not useful. That’s why we use dE(version) or ever newer approaches.

    This probably matters more for 3D LUT generation or overall verification. But all I’m concerned about is White Point. Isn’t 2D space fine when doing Perceptual Match. Rather then XYZ.

    Same as above.

    Also a counter expalme to show that your stattement is false (link from prad.de, deltaC uniformity errors)

    Uniformity is not Proffesional Monitor type Uniformity. But it is better then other Consumer  OLED’s. Especially the LG series that have shit Uniformity by comparison. They have really bad panel lottery.

    • This reply was modified 3 weeks, 5 days ago by EP98.
    • This reply was modified 3 weeks, 5 days ago by EP98.
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    #37585

    pasi123567
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    If you are matching by eye a spectro meter won’t mater.

    I thought it can more accurately match colors without being display technology dependent? Maybe I am wrong I am not too knowledged about the subject of calibration.

    Try to measure on the center and always calibrate to that same spot. Trying to compensate for poor uniformity and averaging out the entire display is probably what’s causing issues.

    I did this enough times. I just also tried using different spots as well but it didn’t help with my color offset. I really just think its not possible at this point and that my displays will never be accurate.

    I wish modern displays had this feature. We can correct any bad Uniformity with it.

    I ike this idea of uniformity matching, never heared any display had this integrated. The demand for a feature like this is probably not very high, hence why it’s no longer a thing. I am sure this could be handled with software as well though.

    #37589

    EP98
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    I thought it can more accurately match colors without being display technology dependent? Maybe I am wrong I am not too knowledged about the subject of calibration.

    You can have some of the most High End Profesional Spectroradiometer Color Probes on the market like a Photo Research, Colorimetry Research & Jeti, that can measure down to 2nm, that cost several thousands of dollars, and you still won’t be able to match displays calibrating them to the same White Point D65 cordinates. You still will see metameric failure and the displays still will need to be perceptually matched.

    I ike this idea of uniformity matching, never heared any display had this integrated. The demand for a feature like this is probably not very high, hence why it’s no longer a thing. I am sure this could be handled with software as well though.

    Excellent Uniformity is in high demand in the professional market.

    The BVM CRT display I have was a extremely high end display geared for the pro market and retailed around $15k for the 20 inch model. So it has features that normal consumer displays don’t have. Along with much better quality control. The biggest size was a 32 inch model and that retailed for about $40k.

    The Successor to the CRT, the BVM OLED model does not have the Uniformity Adjustment built it loke the CRT model. Instead Sony uses a LUT to correct for Uniformity at the factory. They measure different points on the screen and create a lut to correct for that.

    I did this enough times. I just also tried using different spots as well but it didn’t help with my color offset. I really just think its not possible at this point and that my displays will never be accurate.

    Yeah it is extremely hard. It took alot of work just to get my displays to match White Point. I know many people that just completely gave up and just calibrate all displays to D65, with metameric failure and all, because they themselves had so much trouble to get them to match. They completely gave up on the perceptual match process.

    I do think a better method needs to happen.  It just causes people big headaches if I were to be honest.

    • This reply was modified 3 weeks, 5 days ago by EP98.
    • This reply was modified 3 weeks, 5 days ago by EP98.
    #37600

    Vincent
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    It should not be related to DisplayCAL as explained previpusly. IF there is a bug, it’s likely to be in collink.

    I meant i’m using the latest version of argyll.

    Useless statement. Measure it, you have the tools. Dell & Benq also advertise a lot of cool features in their displays but we cannot take them fro granted since sometime their QC is not what we expected.

    It’s not a useless statement as I’m using a Sony BVM CRT. And I did measure many different parts of the screen.  That’s the only way to do a full digital uniformity adjustment.

    I uploaded pictures of the Uniformity Adjustment menu.

    See that black square on the screen. I can change its size to be smaller or bigger. And I can move it anywhere I want on the screen. And adjust White Balance and Contrast for that specific spot on the screen and only that specific spot within that square.

    I know my screen is uniform since I manually did Uniformity Adjustment myself and measured different parts of the screen.

    “And I did measure many different parts of the screen. ” That’st the missing part in your previosu statement that will have saved us time.

    I wish modern displays had this feature. We can correct any bad Uniformity with it.

    Also CIE xy is not perceptually uniform so compare “distance errors” in that 2D space is not useful. That’s why we use dE(version) or ever newer approaches.

    This probably matters more for 3D LUT generation or overall verification. But all I’m concerned about is White Point. Isn’t 2D space fine when doing Perceptual Match. Rather then XYZ.

    No, use dE distance for WRGBCMY.

    Same as above.

    Also a counter expalme to show that your stattement is false (link from prad.de, deltaC uniformity errors)

    Uniformity is not Proffesional Monitor type Uniformity. But it is better then other Consumer  OLED’s. Especially the LG series that have shit Uniformity by comparison. They have really bad panel lottery.

    Yes, I’ve seen WOLED hall of horrors in AVS Forum, uniformity thread.

    But sicne QD is just a LED backlight it’s not better or worse than any other modern widegamut led backlights like WLED PFS. I would say that PFS are more uniform overall for the same QC costs, that’s why even “sRGB only” displays use that backlight. The cheap panels (P3 green, near sRGB native red due to a “hump” in shorter red channel wavelength) with statistically good behavior wins in cost to the additional cost of a lut-matrix for primaries simulation.
    You can see this displaycal colorimeter database. It’s fun of these WLED PFS have entered on sRGB display consumer market… and if they did that if because of  getting the same QC for less money.

    #37601

    Vincent
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    If you are matching by eye a spectro meter won’t mater.

    I thought it can more accurately match colors without being display technology dependent? Maybe I am wrong I am not too knowledged about the subject of calibration.

    It works as EP98 explained to you above. The source of error/mismatch is not in the ultra precise equipment but in your eyes/visual system(eyes-brain).

    Spectral power distribution (SPD, “amout energy per wavelegth” to explian it in a simplified way) is weighted agaisn a “model” of human vision: standard observer.
    This model is a “mean”. You can have an slightly different response but overal mean when you compare lots of people behave like the model.
    The more narrow peaks SPD has, the more probable is that your eyes differ form std observer in that tiny wavelength region where the peak is.

    A laser RGB proyector will have lots of this issues while a White LED (blue led + yellow phosphor, sRGB only coverage) should be less prone to these issues.

    #37602

    Vincent
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    You can see this displaycal colorimeter database. It’s fun HOW these WLED PFS have entered on sRGB display consumer market… and if they did that if because of  getting the same QC for less money.

    Typo, I cannot edit.

    #37607

    EP98
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    “And I did measure many different parts of the screen. ” That’st the missing part in your previosu statement that will have saved us time.

    I thought this was implied when I said I did a full uniformity adjustment.

    But sicne QD is just a LED backlight it’s not better or worse than any other modern widegamut led backlights like WLED PFS

    Generally these QD OLED’s have been praised for very good uniformity on a consumer display. And I believe Samsung or Sony, one of those two, said that it’s much easier to get uniformity better on QD-OLED then on WRGB OLED.

    But this is only for this year’s models when they are trying to impress with this new technology. Next year they may have worse QC control and have bad uniformity.

    And usually you would want to measure uniformity after break in period.

    This model is a “mean”. You can have an slightly different response but overal mean when you compare lots of people behave like the model.
    The more narrow peaks SPD has, the more probable is that your eyes differ form std observer in that tiny wavelength region where the peak is.

    So basically something like a CRT would look similar to most observers.

    But narrow peaks of modern displays, ones that are wide gamut, will start to cause issues among different people. More people will differ from standard observer looking at a QD OLED then looking at a CRT.

    Which can cause lots of issues. Especially when the goal is to match a Reference Monitor for video.

    It looks like people will need a custom White Point specific for their eyes.

    A laser RGB proyector will have lots of this issues while a White LED (blue led + yellow phosphor, sRGB only coverage) should be less prone to these issues.

    For my eyes I’ve seen this issue on WLED LCD’s. 90% sRGB coverage.

    I’ve compared various displays. Using the D65 CRT as reference for White Point. QD-OLED, RGB OLED, WRGB OLED, QD-LCD, WLED LCD, Wide Gamut CCFL LCD, and none of these displays match White Point to the CRT to my eyes. And none matches each other.

    The only display I’ve seen that matches the CRT is a very crappy CCFL LCD that has about 70% sRGB coverage.

    • This reply was modified 3 weeks, 4 days ago by EP98.
    • This reply was modified 3 weeks, 4 days ago by EP98.
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    #37613

    Vincent
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    So basically something like a CRT would look similar to most observers.

    No, that’s false.  Take a look on CRT’s SPD.
    But standard CCFLs peaks are placed where std observer functions’ derivative is close to 0 so even spectrophotometers with broad wavelength step  may measure it properly (tiny wavelength placement errors result in the same measure)

    But narrow peaks of modern displays, ones that are wide gamut, will start to cause issues among different people. More people will differ from standard observer looking at a QD OLED then looking at a CRT.

    No. The issue, if any, it’s due to blue, same as RGB OLED reference monitors. Take a look on SPD+Std obs before making uneducated guess.
    QLED or green or red should offer the same kind of metameric failure as older technologies.

    For my eyes I’ve seen this issue on WLED LCD’s. 90% sRGB coverage.

    I’ve compared various displays. Using the D65 CRT as reference for White Point. QD-OLED, RGB OLED, WRGB OLED, QD-LCD, WLED LCD, Wide Gamut CCFL LCD, and none of these displays match White Point to the CRT to my eyes. And none matches each other.

    The only display I’ve seen that matches the CRT is a very crappy CCFL LCD that has about 70% sRGB coverage.

    If you take a look on RIT paper on observer variability you would see that widegamut “broad” SPD (NEC DLP and Panasonic LCD proyectors) have the same order of magnitude in variability elipsoids as CRTs.

    It may just happen that your z-bar is statistically far from CIE 1931 2 degree. Did you try with 2012? It has huge correction on blue.

    #37618

    EP98
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    No, that’s false.  Take a look on CRT’s SPD.
    But standard CCFLs peaks are placed where std observer functions’ derivative is close to 0 so even spectrophotometers with broad wavelength step  may measure it properly (tiny wavelength placement errors result in the same measure)

    No. The issue, if any, it’s due to blue, same as RGB OLED reference monitors. Take a look on SPD+Std obs before making uneducated guess.
    QLED or green or red should offer the same kind of metameric failure as older technologies.

    Sorry, It wasn’t an educated guess more like somebody told me that. And I was told CRT and CCFL LCD were best to use for perceptual matching.

    So I started reading this paper

    https://s3.cad.rit.edu/cadgallery_production/storage/media/uploads/faculty-f-projects/1304/documents/239/modeling-observer-metamerism.pdf

    It looks like Metameric Failure is due to spectral power distribution of the display.

    NEC 3000 digital cinema projector will be less likely to suffer metameric failure due to it’s wider SPD distribution compared to ITU-R Rec. 2020 RGB laser projector. The NEC 3000 digital cinema projector has a much wider primaries so that’s what causes less of an issue with Metameric Failure. While the ITU-R Rec. 2020 RGB laser projector has very narrow primaries so more likely to cause issue with metameric failure.

    The CRT has very narrow red primary so will also cause some issue with Metameric Failure. So best display to use will be one with much wider primaries to use for perceptual match process, if I understand that correctly. Possibly CCFL LCD, there is a very small difference between that and the CRT. CRT is a tad bit more red then CCFL. But CCFL was the closest to CRT of all the displays I used.

    If you take a look on RIT paper on observer variability you would see that widegamut “broad” SPD (NEC DLP and Panasonic LCD proyectors) have the same order of magnitude in variability elipsoids as CRTs.

    It may just happen that your z-bar is statistically far from CIE 1931 2 degree. Did you try with 2012? It has huge correction on blue.

    I have been messing with Alternate CMF’s in Jeti software. So what would be the best CMF for me to use? I converted a D65 CRT to Alternate CMF’s to have a target White Point to use with these CMF’s These coordinates with each of these CMF’s on the CRT will give me the exact same result as calibrating the CRT to 1931 D65. And I used these coordinates to calibrate other display tech to see if they match a D65 1931 CRT. But since CRT may not be best to use for perceptual match process which display tech would you recommend? And how would I figure out which CMF would be best to use?

    CIE 1964 10*
    X: 0.3149
    Y: 0.3310

    Judd Vos 1978 2*
    X: 0.3183
    Y: 0.3408

    CIE 2006 2*
    X: 0.3152
    Y: 0.3327

    CIE 2006 10*
    X: 0.3142
    Y: 0.3303

    CIE 2006 2* Schanda-Csuti mod
    X: 0.3196
    Y: 0.3403

    CIE 2006 2* TU IImenau mod
    X: 0.3171
    Y: 0.3363

    CIE 2006 10* TU IImenau mod
    X: 0.3160
    Y: 0.3336

    I do have a RGB BVM OLED and I found CIE 2006 2* TU IImenau mod matched better with BVM CRT. I found issues with Judd Modified CMF Sony uses. Still looks more green then CRT.

    • This reply was modified 3 weeks, 3 days ago by EP98.
    • This reply was modified 3 weeks, 3 days ago by EP98.
    • This reply was modified 3 weeks, 3 days ago by EP98.
    • This reply was modified 3 weeks, 3 days ago by EP98.
    #37623

    EP98
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    When I calibrate all display to D65 1931 compared to CRT,

    RGB OLED looks too green

    RGB OLED using Sony’s Judd modified CMF looks less green then D65 1931, but still a bit more green then CRT.

    WLED LCD looks more red

    QD-LCD looks even more red then WLED LCD

    #37624

    EP98
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    I have the Jeti 1501 Hi Res version by the way that can measure down to 2nm. just so you know the probe I’m working with.

    #37625

    EP98
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    It may just happen that your z-bar is statistically far from CIE 1931 2 degree. Did you try with 2012? It has huge correction on blue.

    Sorry for the back to back replies but I found this paper from Jeti

    https://www.jeti.com/files/content/support/downloads/papers/Lux%202017.pdf

    They tested CCFL LCD and LED LCD and found CIE 2006 2* TU IImenau mod equalized white point for those two technologies. Which I also found that this CMF also equalized CRT and RGB OLED. Although the XY targets are different in the paper for D65. I might try those targets.

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