Measuring contrast and color uniformity

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  • #31155

    Halfwit
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    I own the X-Rite i1Display Pro calibrator and am using DisplayCAL to test and calibrate my monitor(s). Two questions:

    1. Is there a way to measure the static contrast ratio of the monitor in DisplayCAL?
    2. Is there a way to measure color uniformity across the panel (is that the DeltaE value in the Tools >  Report > Measure display device uniformity test, as circled on the screenshot below)?

    Thank you!

    i1Display Pro on Amazon  
    Disclosure: As an Amazon Associate I earn from qualifying purchases.

    #31156

    Vincent
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    1- Measurement report or faster: calibrated or uncalibrated display report (log window and less patches)

    2- it is what you did, but dE is overall error, color + brightness. Change central cell combo box to see them separated in delta C (severity of color tint) and brightness.
    Usually bad quality panels suffer more visible color uniformituy issues (dC). Up to -10/15% brightness on corners are somehow expected unless some kind of uniformity compensation (UC) is applied… and that is going to destroy contrast, the worse panel “native uniformity” is, the more is going to be destroyed. Example: 1000:1 IPS goes to 500-600:1 on bad quality panels when UC is applied.

    #31157

    Halfwit
    Participant
    • Offline

    1- Measurement report or faster: calibrated or uncalibrated display report (log window and less patches)

    2- it is what you did, but dE is overall error, color + brightness. Change central cell combo box to see them separated in delta C (severity of color tint) and brightness.
    Usually bad quality panels suffer more visible color uniformituy issues (dC). Up to -10/15% brightness on corners are somehow expected unless some kind of uniformity compensation (UC) is applied… and that is going to destroy contrast, the worse panel “native uniformity” is, the more is going to be destroyed. Example: 1000:1 IPS goes to 500-600:1 on bad quality panels when UC is applied.

    Fantastic, thanks for your valuable input!

    I do have one more question: is there a way to get a color gamut CIE diagram in DisplayCAL, one that would show me sRGB/Adobe RGB/DCI-P3 coverage pre- and post-calibration?

    #31158

    Vincent
    Participant
    • Offline

    1- Measurement report or faster: calibrated or uncalibrated display report (log window and less patches)

    2- it is what you did, but dE is overall error, color + brightness. Change central cell combo box to see them separated in delta C (severity of color tint) and brightness.
    Usually bad quality panels suffer more visible color uniformituy issues (dC). Up to -10/15% brightness on corners are somehow expected unless some kind of uniformity compensation (UC) is applied… and that is going to destroy contrast, the worse panel “native uniformity” is, the more is going to be destroyed. Example: 1000:1 IPS goes to 500-600:1 on bad quality panels when UC is applied.

    Fantastic, thanks for your valuable input!

    I do have one more question: is there a way to get a color gamut CIE diagram in DisplayCAL, one that would show me sRGB/Adobe RGB/DCI-P3 coverage pre- and post-calibration?

    ¿Visually? DisplayCAL-profile-info.exe shows a plot in 2D o 3D in CIE xy or a*b* of the CURRENT display profile assigned to each display on OS.

    Also when you profile a display after profile is created it shows a summary with that visual info and intersection (coverage) & volume (mosty useless fro an user) % values.

    If you want to validate factory calibration or HW calibration, then make a profile without calibration (all calibration tab settings to native/as measured) and after profile is cretaed it will show that info.

    If you want to calculate those intersection values for an already existing profile you’ll have to use command line. Go to argyll website and see doc of “iccgamut” and “viewgam” tools. One creates a gam file with profile volume info an the other one can plot or intersect it (or something close to that). Keep in mid that some profies store whitepoint as PCS whietpoint (d50) so maybe you do not want to use absolute intent for them, that includes 2D or 3D CIE xy/a*b* plot.

    PS: If you are useing an Xrite spectro use 3nm high res mode and if you are using a colorimeter a suitabel correction for your display backlight must be configured, otherwise measured values (specially for whitepoint) will be off actual values.

    • This reply was modified 1 month, 1 week ago by Vincent.
    #31160

    Алексей Коробов
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    If you want to calculate those intersection values for an already existing profile you’ll have to use command line.

    User can do it without command line in Windows/Linux: tap on Profile Loader icon (circular rainbow-painted arrow) with right mouse button, open Profile Associations dialogue, add profile you’re interested in and push Profile Info button. Select some standard profile for comparison. Better to use 3D plot cause colour have three coordinates, better to compare in L*a*b space cause it supports metrics, RGB-like is not informative. Want to compare with user-made profile? Then copy it to Argyll\ref folder and restart Profile Loader (close and open from start menu). Argyll is usually placed in “C:\Users\<current_user>\AppData\Roaming\DisplayCAL\dl” folder in Windows, Linux users should find it on their own. Profile Info doesn’t show graphs in newer MacOSs, it is still not updated to this bugware.

    Note that Profile Info generates rough 3D plots, you need command line to get detailed images, simply set 2.5…4.0 step and be patient.

    #31169

    Vincent
    Participant
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    Nice to know that it can be done by UI. Thanks for the shortcut.

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