Gamut Coverage and Hardware sRGB Clamp

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  • #33345

    tmfrank
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    I am very much a beginner in this subject. I am trying to see what gamut coverage my monitor has in its various color modes. But for some reason, both profiling and calibration reports show the exact same gamut coverage and volume regardless of my monitor settings.

    I have a MSI MAG274QRF-QD with updated firmware. This provides various color modes (“clamps”) including User (default), sRGB and Display P3. I ran calibration and profiling in each of these settings and found the reported coverage unchanged. Attached is a screenshot of the report under each of these settings.

    Am I doing/reading it wrong or is the monitor not working as expected? To my eye there seems to be a change but that also may because other settings are changing when changing modes as opposed to clamping the gamut.

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    #33357

    Алексей Коробов
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    Either you change color temperature instead of coverage, or these modes aren’t realized as it should be. Check also special settings like gaming ones or those, that are not considered to influence on gamut. Sometimes strange things happens. On the last week I’d met a display that shows good contrast with working FreeSync only. Seems that your display doesn’t cover full P3, so P3 and User modes mean maximal gamut. But sRGB mode limits RGB primaries and gamut as normal. Also note that gamut size and most saturated colors coverage depend on white point. Use the fastest calibration/profiling settings and colorimeter test target for experiments, this will save your time.

    #33358

    tmfrank
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    So I confirmed that the settings I am changing in the OSD are the correct ones per the manufacturer.  To my untrained eye, I do feel that the sRGB is indeed bringing down the saturation compared to the User or P3 modes. To be clear, I should be seeing a lower coverage for the wider gamuts in the report right (assuming the sRGB mode is working)?

    Display definitely is not 100% P3 so not surprised about that. As far as I can tell the only settings that changed in the OSD between my tests is the color mode. Even brightness and “RGB” color temp settings were the same.

    Seems that your display doesn’t cover full P3, so P3 and User modes mean maximal gamut. But sRGB mode limits RGB primaries and gamut as normal.

    Are you saying this is what is should be doing or do you see this reflected in the screenshot?

    Use the fastest calibration/profiling settings and colorimeter test target for experiments, this will save your time.

    Yes thank you I have been doing that on subsequent tests. Just had this screenshot from calibration handy. Even the profiling tests show the same results.

    #33359

    Алексей Коробов
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    Your screenshots show full near-P3 coverage, there’s no sRGB  limitation. Working sRGB mode/preset limits coverage to something +/- close to dashed line on your gamut graph. There’s something wrong if you see decreased saturation in sRGB display mode, but Profile Info shows near-P3 gamut. This means that you haven’t changed system screen profile after you’ve changed display mode. Have you built separate profiles for User and sRGB modes? If no, you make essential mistake. Note, DisplayCAL Profile Loader can’t switch system screen(s) profile(s) automatically. Some proprietary tools (Eizo, BenQ) can do this when display with USB-backlink is used. But Profile Loader allows to do the same in five mouse clicks.

    You should switch output intent to relative colorimetric in Profile Info to get correct comparison when you use non-6500K white point.

    Why do you set sRGB gamma in DisplayCAL? This may only be actual for sRGB display mode/preset, set 2.4 for Rec.709 mode (if avaible) and 2.2 in general. Old enough sRGB standard uses gamma 2.2 except of dark region, when gamma is 1 (linear lightness growth). This leads to conversion problems and mishmash in some cases. By example, some displays have sRGB mode that uses sRGB gamma, but some others have sRGB mode that uses gamma 2.2, cause gamma 2.2 is recommended for consumer displays ans is used in most cases. You should also know that LCD displays can’t hold gamma 2.2 in a full 8-bit range cause they use some emulation. This tranfer law was developed for CRT displays where this function was a part of device nature.

    #33360

    tmfrank
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    Have you built separate profiles for User and sRGB modes?

    Yes I have a unique profile for each color mode that I have to switch manually when needed. But the decreased saturation that I think im seeing is with all profiles disabled.

    Your points on output intent and gamma are noted though, I will look at that next time I calibrate. Right now im more concerned that the monitor is broken. It seems im testing with DisplayCAL properly but still seeing no clamp. I guess I’ll try to reset the monitor and try again before potential RMA.

    #33558

    Anonymous
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    #33560

    tmfrank
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    Just wanted to post what I learned in case someone else is encountering the same problem.

    The sRGB mode (gamut clamp) on the MSI MAG274QRF-QD  does NOT work if any other settings are changed in the OSD. Using the sRGB mode/clamp does not lock you out of any of the other picture settings in the OSD. However, if you do change any of the settings from their default, it effectively disables the sRGB gamut clamp. The OSD still shows you are in the sRGB “mode” but it is effectively displaying the “User” (default) mode. This seems to be behavior for all non-default color modes available in the OSD.

    • This reply was modified 1 week ago by tmfrank.
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