Several questions about calibration and profiling

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  • #26058

    Timill
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    Does lowering the RGB gain controls in monitor OSD limit the panel’s native colour gamut? I’ve noticed that it does reduce brightness. RGB gain limits light output of that colour so wouldn’t it reduce the gamut coverage possibility of the panel?

    How can I tell which gamma setting in my monitor to use before profiling? Do I just go by the average number listed in the output of “report on uncalibrated display device”? If I’m calibrating a 3000:1 VA panel to Rec. 1886, should I go with the “Gamma 2.2” option which gives an average output of 2.3 according to report, or the “Gamma 2.4” option which gives an average output of 2.5 according to report? Which is closer to the eventual output of Rec. 1886 on a 3000:1 panel? Less software correction is better, yes?

    What is the “correct” gamma to use for watching film/TV? I tried 2.4 as it’s considered quite popular but I found that near-black detail was quite crushed looking and hard to discern. Rec. 1886 looks much better with a more balanced looking image.

    What is the relationship between ambient brightness and gamma? Is it possible for me to use the ambient brightness sensor on my i1 Display Pro to set the ideal brightness on my bias light (medialight eclipse)?

    Why does verify calibration report list a different number of colour test patches per monitor? My new VA monitor lists 29 patches every time I do measurement report while my other TN monitor always has the same number (that I can’t remember). Also, are the visual colour comparisons in the colour dE list arbitrary or meant to show an accurate comparison of how “wrong” the colours are?

    Is there any conflict with having Windows handle the white point and gamma calibration while my media player (mpv with –icc-profile-auto) handles the colour transform? Is that the correct way to do things?

    What exactly is the relationship between colour gamut coverage and colour accuracy? Does under-coverage of a gamut (let’s say sRGB) necessarily mean that some colours are counted as inaccurate because the panel can’t produce them, or do missed colours not get counted in the accuracy report? Is it possible for a display to have exactly 100% sRGB volume and coverage (no under or over-coverage) but still have inaccurate colours?

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    #26068

    Vincent
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    Does lowering the RGB gain controls in monitor OSD limit the panel’s native colour gamut? I’ve noticed that it does reduce brightness. RGB gain limits light output of that colour so wouldn’t it reduce the gamut coverage possibility of the panel?

    No, it should not (gain control is different form saturation control).
    Yes, it also reduces contrast. Native panel contrast is at natve white. The further you move from it the lower contrast is. You limit max output, but back color leak on LCDs remain there.

    How can I tell which gamma setting in my monitor to use before profiling? Do I just go by the average number listed in the output of “report on uncalibrated display device”? If I’m calibrating a 3000:1 VA panel to Rec. 1886, should I go with the “Gamma 2.2” option which gives an average output of 2.3 according to report, or the “Gamma 2.4” option which gives an average output of 2.5 according to report? Which is closer to the eventual output of Rec. 1886 on a 3000:1 panel? Less software correction is better, yes?

    You can try to run a profile verification with grey scale charts at these OSD settings so you can see actual gamma vs input plot instead of an average.

    What is the “correct” gamma to use for watching film/TV? I tried 2.4 as it’s considered quite popular but I found that near-black detail was quite crushed looking and hard to discern. Rec. 1886 looks much better with a more balanced looking image.

    On low contrast displays you have to choose the lesser evil (usually 2.4) but with an VA you can try Rec1886

    What is the relationship between ambient brightness and gamma? Is it possible for me to use the ambient brightness sensor on my i1 Display Pro to set the ideal brightness on my bias light (medialight eclipse)?

    Do not use it if you are going to sue color managed apps. It will be undone and you loose unique grey levels for nothing.

    Why does verify calibration report list a different number of colour test patches per monitor? My new VA monitor lists 29 patches every time I do measurement report while my other TN monitor always has the same number (that I can’t remember). Also, are the visual colour comparisons in the colour dE list arbitrary or meant to show an accurate comparison of how “wrong” the colours are?

    You choose testchart, so you chose diffrent testchart in the past. Verification is done against profile itself unless you configure other thing.

    Is there any conflict with having Windows handle the white point and gamma calibration while my media player (mpv with –icc-profile-auto) handles the colour transform? Is that the correct way to do things?

    Let displaycal (not windows) load grey calibration to avoid banding if your GPU can actually do it. Profile is post calibration monitor description (gamut + TRC) so calibration has little to do with it. An exception is a  software LUT3D which can use VCGT calibration in its computation, for example madVR.

    What exactly is the relationship between colour gamut coverage and colour accuracy? Does under-coverage of a gamut (let’s say sRGB) necessarily mean that some colours are counted as inaccurate because the panel can’t produce them, or do missed colours not get counted in the accuracy report? Is it possible for a display to have exactly 100% sRGB volume and coverage (no under or over-coverage) but still have inaccurate colours?

    Default verification is against display profile itself, hence has nothing to do with colorspace coverage, just test if profile describes mnonitor behavior in an acurate way.
    Profile verification with similation profile (sRGB) but NOT set as display profile on the other checkbox validates what you ask, if under a color managed app like photoshop your display can render that simulated colorspace colors in an accurate way, with the colors set in testchart. The outer gamut colors are, more high dE, but also if profile is not accurate dE can be high even ifif coverage is 100%.
    Hence first validate if profile is a good description of monitor (default with no other selections)

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