calibrate HDR display on Windows HDR mode

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  • #26089

    nelldrip
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    Hello everyone

    Generally, HDR displays or TVs often have inaccurate tone maps and color tones, I think calibration is preferable for them.
    However, HDR calibration is difficult and it is limited to professional monitors that support 3D LUTs.

    DisplayCal supports only madVR or DaVinci Resolve which can use 3D LUTs, monitor calibration does not support HDR.
    I think it is because the calibration of the monitor depends on icc, icc is not support HDR.

    However, VCGT can be used to calibrate general HDR displays and TVs.
    It is not possible to adjust the color gamut or saturation like 3D LUT, but VCGT can handle the optimization of brightness mapping and white balance.

    Profiling for madVR, measure the brightness range of the target display, and choose a hard clip for the tone curve and put the measured brightness value as the target brightness in LUT tab.
    Black offset set as 0.

    Measurement is performed in this state, and create 3D LUT in IRIDAS format.

    When apply the output LUT (I call it as hardclip.cube) as VCGT of the target display, the white balance and brightness will be correct for the displayable brightness range.
    However, in this state, the brightness than displayable range will be clipped, it will not favorable for viewing.

    It can solve by combining appropriate tone maps.
    Specifically, input the LUT (hardclip.cube) to the software that can operate the LUT, place the tone map before the LUT (hardclip.cube), and Output as LUT (I call it as calibrate.cube).
    I think DaVinci Resolve useful for this process, and I used Resolve when I calibrate with this method.

    Apply this LUT (calibrate.cube) as VCGT of the target display.
    I used Lightspace’s LUT coverter and SpaceMan.
    I think there are other ways, such as using the Video Equalizer to adjust VCGT directly.

    If you require further correct the accuracy and look, you can make more preferable adjustments by combining the Video Equalizer and Color HCFR.

    Choose madTPG as the pattern generator in ColorHCFR and measure grayscale.
    At the same time, use VideoEqualizer to adjust the tone map and RGB balance.

    Sure, this is not displaying accurate brightness and color, but it can improve the look on HDR mode.
    For reference, I attache the luminance responce and gray scale of my BenQ EW3270U before and after the actual calibration.

    EW3270U looks on HDR mode is not so good, but this calibrate succeeded to get it closer to the calibrated PA32UCX.

    If DisplayCal can load the IRIDAS 3D LUT directly into the VCGT as a 1D LUT, or edit the VCGT on the DisplayCal, I think it will be very easy to make adjustments in this way.

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    #26415

    namefaceguy
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    I really hope there becomes an easier way to do this.  I have the same monitor and it is fantastic besides the terrible HDR calibration.  I just got a odyssey g7 and have much better hdr on this monitor but it lack 4k and the ability to  to receive 4k netflix.  This seems awefully complex for someone of my skill level though I have just started trying to use HCFR.  How complicated would you say it would be to learn?

    #26418

    nelldrip
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    The process itself is easy, but it’s a fact that it takes a bit of work to do it.
    The same work can be done by directly performing VCGT with ColorHCFR and VideoEqualizer without using DisplayCal LUT, and currently I think that is easier.

    For reference, the LUT for Video Equalizer is attached.

    328p6vubreb / ​​11 (VESA HDR600 mode)
    https://mega.nz/file/HrpAQZDR#SM7jTdKHQ4Jrz8v9rZeo7elXae2roBWuplUIts8wCO8
    EW3270U (cinema HDR mode)
    https://mega.nz/file/z2QDkSAA#i7M_ar5raxGLnJw9B3__4JPgiOidWjU9nkEhKZuB4FM

    #26454

    namefaceguy
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    I’ve never used Video Equalizer and can’t seem to find the program when I google it for some reason.  Is it just part of HCFR?  I’m just barely learning how to use that program as well.  Any tips on resources where I can gain understanding?

    #26455

    namefaceguy
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    Alright I did some experimenting and I combined my initial technique with my newfound knowledge of how to use hcfr and found out that I could simply use the nvidia control panel color settings to fix the appearance of hdr.  Im not sure what video equalizer is or if its just a generic term for any video equalizer but this is much better than before where I was just watching youtube videos and trying to calibrate with the nvidia control panel settings by eye.  Let me know if you find any other way of solving this problem.  I got my graphs looking very good.

    #26463

    nelldrip
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    #26470

    namefaceguy
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    Hell yes.  Thank you.  Because your post I’ve learned HCFR and now Im learning this. Your kindness is going to possibly change my life.

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