Do I need to calibrate my monitor's HDR mode?

Home Forums General Discussion Do I need to calibrate my monitor's HDR mode?

This topic contains 7 replies, has 3 voices, and was last updated by  Florian Höch (@fhoech) 4 weeks, 1 day ago.

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  • #20084

    hengisme3 (@hengisme3)
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    The monitor “supports” HDR although it’s only 350 nits.

    I read that HDR movies should at least look as good as the SDR version with a better colour gamut even if the screen does not support higher nits for meaningful HDR. But when I tested HDR Blu-ray movies on the screen they looked notably worse than the SDR versions of the same movie did.

    Am I supposed to also calibrate the HDR mode somehow, and have a profile set up on DisplayCal just for the HDR mode? If so, what settings should I use? I’m assuming “Default” wouldn’t quite work the same for this.

    Another question is: Since the DisplayCal Profile Loader deactivates when I’m watching movies with madVR, does the calibration even affect the image in any way?

    #20091

    Florian Höch (@fhoech)
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    Another question is: Since the DisplayCal Profile Loader deactivates when I’m watching movies with madVR, does the calibration even affect the image in any way?

    No (unless you have an nVidia card and enable “video overlay” in madVR options – calibration will then stay active for the desktop except for the video).

    #20095

    SirMaster (@sirmasterboy)
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    Maybe this already goes without saying, but I will add my knowledge on this because I think it is helpful.

    In madVR, in the calibration tab for the display there is a checkbox called “disable GPU gamma ramps”

    https://wiki.jriver.com/index.php/File:03-calibrationoluk8.png

    If this box is checked, your madVR media player will have no calibration. If this box is unchecked, then you will have a basic 3x 1DLUT calibration even for the madVR video.

    If you want to take advantage of the wider color gamut though read on.

    I have never used an HDR PC monitor, but I would imagine that the DCI-P3 color space only activates when the monitor is put into HDR mode. I assume you already tried using this mode, but were not satisfied with its performance.

    However, the backlight of the monitor is really what determines your ultimate color gamut coverage, now you just need a way to convert the rec709 or SRGB color coordinates that your monitor is using in it’s non-HDR mode to DCI-P3 coordinates so you can enjoy the wider color gamut in your HDR videos. You can do this by creating a 3DLUT in DisplayCAL, which madVR supports using.

    In DisplayCAL, choose “Video 3D LUT for madVR (D65, Rec 709 / Rec. 1886)” option on top.

    Pick your normal settings in “Display & Instrument” leaving madVR as the Display selection.

    In “Calibration” tab, I recommend selecting “Gamma 2.2” as the “Tone curve”, everything else can stay.

    In the “Profiling” tab choose a reasonable number of patches, I recommend about 175 or 425 depending on the speed of your meter but feel free to do more.

    In the “3D LUT” tab choose “DCI-P3/SMPT-431-2 D65” for the Source Colorspace, and Gamma 2.2 again for the Tone curve. Finally for Input encoding choose TV RGB 16-235 (clip WTW).

    Then go ahead and run the calibration and profile. When it’s done it will ask if you want to install the 3D LUT into madVR so go ahead and do this.

    You should now get the wider color gamut when watching HDR videos. Also in madVR make sure in the “hdr” tab you choose “tone map HDR using pixel shaders” and enter in your screens peak nits. I would actually measure your screen’s NITS with the DisplayCAL interactive display adjustment window to see what your peak NITS actually are because it might not actually be 325. You can also just set the HDR peak nits setting to whatever looks best to you as well.

    This is the process I use for my laptop which has a backlight that is near DCI-P3 primaries and around 300 nits and the results for the HDR video looks excellent.

    Hope this helps.

    #20109

    hengisme3 (@hengisme3)
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    I have never used an HDR PC monitor, but I would imagine that the DCI-P3 color space only activates when the monitor is put into HDR mode. I assume you already tried using this mode, but were not satisfied with its performance.

    However, the backlight of the monitor is really what determines your ultimate color gamut coverage, now you just need a way to convert the rec709 or SRGB color coordinates that your monitor is using in it’s non-HDR mode to DCI-P3 coordinates so you can enjoy the wider color gamut in your HDR videos. You can do this by creating a 3DLUT in DisplayCAL, which madVR supports using.

     

    Thanks, I’ll definitely look into this.  Does all this mean that the monitor doesn’t have to be in HDR mode to be able to view HDR stuff?

    One thing is that I’m fairly certain the screen is in wide-gamut even in SDR mode,  unless a special sRGB mode is toggled on.

    Do I “lose” anything when doing some kind of conversion from HDR to SDR? Or is that what the monitor would have to do anyway so there’s no real difference?

    On my old monitor which did not support HDR, I used to watch HDR movies using madVR’s conversion to SDR using pixel shaders after processing the movie file with the madMeasureHDR tool. The end result was very watchable, but still much inferior to the normal SDR version when it comes to bright effects (like lightning effects of Thor, for example).

    I hoping that with a monitor that supported HDR I could dodge this whole conversion thing all together.

    • This reply was modified 1 month ago by  hengisme3.
    #20111

    hengisme3 (@hengisme3)
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    Another question is: Since the DisplayCal Profile Loader deactivates when I’m watching movies with madVR, does the calibration even affect the image in any way?

    No (unless you have an nVidia card and enable “video overlay” in madVR options – calibration will then stay active for the desktop except for the video).

    So the only way to make sure that the video’s image is calibrated is to use the 3dlut options?

    #20119

    SirMaster (@sirmasterboy)
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    Another question is: Since the DisplayCal Profile Loader deactivates when I’m watching movies with madVR, does the calibration even affect the image in any way?

    No (unless you have an nVidia card and enable “video overlay” in madVR options – calibration will then stay active for the desktop except for the video).

    So the only way to make sure that the video’s image is calibrated is to use the 3dlut options?

    As I mentioned, video only gets the 1DLUT calibration (gamma and greyscale white balance) if you keep the “disable gamma ramps” checkbox unchecked.

     
    I have never used an HDR PC monitor, but I would imagine that the DCI-P3 color space only activates when the monitor is put into HDR mode. I assume you already tried using this mode, but were not satisfied with its performance.
    However, the backlight of the monitor is really what determines your ultimate color gamut coverage, now you just need a way to convert the rec709 or SRGB color coordinates that your monitor is using in it’s non-HDR mode to DCI-P3 coordinates so you can enjoy the wider color gamut in your HDR videos. You can do this by creating a 3DLUT in DisplayCAL, which madVR supports using.
     

    Thanks, I’ll definitely look into this.  Does all this mean that the monitor doesn’t have to be in HDR mode to be able to view HDR stuff?
    One thing is that I’m fairly certain the screen is in wide-gamut even in SDR mode,  unless a special sRGB mode is toggled on.
    Do I “lose” anything when doing some kind of conversion from HDR to SDR? Or is that what the monitor would have to do anyway so there’s no real difference?
    On my old monitor which did not support HDR, I used to watch HDR movies using madVR’s conversion to SDR using pixel shaders after processing the movie file with the madMeasureHDR tool. The end result was very watchable, but still much inferior to the normal SDR version when it comes to bright effects (like lightning effects of Thor, for example).
    I hoping that with a monitor that supported HDR I could dodge this whole conversion thing all together.

    If you are using “tone map HDR using pixel shaders” then no it doesn’t need to be in HDR mode.

    If your monitor is always in DCI-P3 color gamut mode even in SDR mode then all your colors would be really oversaturated. I highly doubt this is the case.

    If that’s truly the case, then in madVR in the calibration tab, you would only get correct color if you choose the “this display is calibrated” and select DCI-P3 from the calibrated to the following primaries/gamut dropdown.

    I’m guessing that doing this will actually make your color look too dull and washed out because your monitor should actually be using rec709 coordinates in all non-HDR modes.

    You don’t really lose anything tone-mapping HDR to SDR as that’s what the monitor has to do anyways. madVR will just it better and with more control. Especially if you use the test builds of madVR which include dynamic tone-mapping. Your monitor would just be doing a simple static tone-map curve, whereas madVR can do dynamic tone-mapping based on each frame of the video when using the madVR test builds.

    Tone-mapping HDR to SDR even on a plain SDR monitor that can only do 100 nits should not produce results that look worse than the SDR version of the video. If it looks worse then you are not using the correct settings in madVR.

    To get the best results you need to be using the test builds of madVR which do dynamic tone-mapping. The release build of madVR only does static tone-mapping.

    #20121

    hengisme3 (@hengisme3)
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    If your monitor is always in DCI-P3 color gamut mode even in SDR mode then all your colors would be really oversaturated. I highly doubt this is the case.

    “Default setup of the screen out of the box was with the full 98% DCi-P3 colour gamut and so you had bright and vivid colours which were noticeably richer than a standard sRGB gamut display. The gamma curve was accurate and overall the image looked very pleasing. It was a little too cool by about 500k and the contrast ratio was only moderate for an IPS panel at around 850:1. For those who want to work with a more common sRGB gamut there is also a very reliable sRGB emulation preset mode available which was great to see, and that carries the LG factory calibration. This too had a reliable gamma curve, more accurate white point and a low dE as well offering very good colour accuracy”

    -https://www.tftcentral.co.uk/reviews/lg_27gl850.htm

    Not sure why this is a thing, but everything looks really good after calibration, even though I know it’s oversaturated in terms of actual accuracy.

    I’ve been using the madVR test builds alongside with the measurement files it generates

    Either way I did a 3DLUT as you suggested and things look good at the moment, but I haven’t really gotten to comparing with an SDR version yet.

    #20128

    Florian Höch (@fhoech)
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    If this box is unchecked, then you will have a basic 3x 1DLUT calibration even for the madVR video.

    Only if you are NOT using a 3D LUT (which includes calibration, and is preferable). This box does not need to be touched (unchecked).

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