Contrast cannot be reached

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  • #36692

    Christopher
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    I’m having an issue within DisplayCAL, when choosing reset video cards gamma table and doing an uncalibrated report. I can reach around 900+ contrast ratio; although, if I do a calibration that number will drop to around 350 contrast ratio but my white point will reach basically D65 almost exactly.

    Therefore how can I get the D65 white point and the contrast ratio that the display is capable of instead of only one of the two. I’m beginning to believe something is preventing both, I’ve checked the video card control panel and I can’t find much to adjust ?

    #36700

    Vincent
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    Mostly user’s fault. You are modifying too much OSD settings. Even if native WP was 10dE ~7000K contrast should drop just above 700-800:1

    #36708

    Christopher
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    I’ve adjusted and resettled almost every OSD setting, nothing works. The only way I can get 800+ contrast ratio is by disabling gamma for the video card, although I cannot write a ICC file with that contrast.

    #36713

    Christopher
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    I think the video card gamma is preventing me from getting the high contrast ratio; 350 is the max roughly I can get in contrast ratio. I can adjust the OSD once, twice, forty times but it won’t increase the contrast it limits to around 350.

    #36715

    Vincent
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    Unlikely unless you did something wrong in configuration. Easy to detect, plot calibration curves and see if it is liftting black or clipping white

    #36739

    Christopher
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    I believe that the GPU is causing the display not to reach the 1000:1 contrast ratio it can reach. The maximum I got recently was roughly 745.

    The Asus calibration software doesn’t even help with calibration it causes more harm then good. Therefore, simply keeping the preset in standard and calibrating has done, I hope; a good Job. I just don’t know how I could reach 1000 contrast from my current contrast amount, if it’s even possible ?

    All this is by using the correct EDR file for the display and doing alot of OSD adjusting. I understand that black level OSD is equal to adjusting white level as well as I learned a few other things with the OSD options. I learned that profiling from it’s preset for example Rec709, can produce an alright result but it may require some fighting.

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    #36755

    Vincent
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    Looks weird in lower end, zoom in. Maybe it’s your fault selecting Rec709 as TRC, you should not, select 2.2 or closest to native gamma, then make a LUT3D to whatever you want (Rec709 primaries, gamma 2.4 relative TRC)

    1000:1 is native white. If WP was too off contrast may drop getting D65 maybe 800:1.

    #36756

    Christopher
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    This is update, contrast is 850:1; from what I understand white point is very close to D65 –  CCT 6536.

    This is very close to 1000:1 but issue is, this number dropping for whatever reason. It’s possible I can go higher but it’s also possible, no !

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    #36762

    Vincent
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    CCT is not a valid way to address a white point, search. You can be exactly 6500K CDT and be >10 dE to D65.

    From screenshot, since *YOU* are limiting green & blue channel max output to get D65 because of display limitations (bad RGB gain behavior) or inexperience 850:1 seems expected.

    Also you are lowering gamma a lot from native in VCGT. Usually with a widegamut you aim to 2.2 or closest to native in native gamut setting, then make a LUT3D to whatever you need for video editing. CHeck if there is some OSD preset with a closer gamma (measured) to 2.2 or your desired TRC.

    • This reply was modified 1 month ago by Vincent.
    #36767

    Christopher
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    Also you are lowering gamma a lot from native in VCGT. Usually with a widegamut you aim to 2.2 or closest to native in native gamut setting, then make a LUT3D to whatever you need for video editing. CHeck if there is some OSD preset with a closer gamma (measured) to 2.2 or your desired TRC.

    The other OSD presets don’t really give better results, I’ll try but I’m skeptical !

    I am limited green and blue but here is one more plotting the gamma curves. This is 845 contrast; as you mentioned it’s probably display limitations this is the best I’ll get. It’s not bad, atleast I’m close to the 1000:1.

    I may adjust white level to try to go a little higher then 850 but the display seems to just cap at 850.

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