3dlut for madvr hdr to sdr2020

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This topic contains 4 replies, has 3 voices, and was last updated by  SirMaster (@sirmasterboy) 2 months, 2 weeks ago.

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  • #19970

    Axelpowa (@axelpowa)
    Participant
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    Hi,

    I’ve been reading about displaycal and it’s 3dlut generation capabilities.

    I’m trying to generate a 3dlut with madvr to use it with my JVC 7500 Proyector and madvr tonemaping.

    I’m having some difficulty with it.

    What would be the recommended settings?

    I select madvr hdr(DCI-P3, bt2020…) and madvr as screen to use the madvrtpg.

    After that I changed the gamma to a gamma 2.4 instead of st2084 because I don’t want to use HDR, instead I use in the Proyector a 2.4 gamma and let madvr do the conversion.

    My goal is to get the color space bt2020 or DCI-P3 with a 2.4 gamma.

    When I start the calibration madvr opens the pattern generator but it seems it sends metadata because the Proyector switches to the HDR profile everytime.

    Is there a way to avoid this?

    Regards!

    #19971

    Florian Höch (@fhoech)
    Administrator
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    Hi,

    When I start the calibration madvr opens the pattern generator but it seems it sends metadata because the Proyector switches to the HDR profile everytime.

    You have to disable HDR mode on madTPG itself (via the respective toggle button) before starting any measurements.

    #19975

    SirMaster (@sirmasterboy)
    Participant
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    It’s switching to HDR because you told DisplayCAL that you are making an HDR 3DLUT by choosing the “Video 3D LUT for madVR HDR (D65 Rec. 2020 / SMPTE 2084 / BT.2390)”

    You must not use this option as this is literally a HDR 3D LUT. You want to use madVR to tone-map HDR to SDR, so as you stated, you will be using SDR2020 which is NOT an HDR 3D LUT.

    You need to choose “Video 3D LUT for mad VR (D65, Rec. 709 / Rec 1886)”

    Then on the 3D LUT tab, you can select your Tone curve to Custom Gamma 2.4 and your source colorspace to BT.2020.

    This will then generate a 3D LUT for madVR which will go in the Devices -> “your device” -> Calibration tab, in the BT.2020 slot.

    When you use this mode madTPG will not need any adjustment and will work find by default.

    The mode that you were choosing before was an HDR 3D LUT which would not go in that tab, but instead would have gone in to Devices -> “your device” -> hdr -> “tone map HDR using external 3DLUT”

    Instead since you are using “tone map HDR using pixel shaders” which makes an SDR 3D LUT appropriate.

    Hope this is clear.

    • This reply was modified 2 months, 2 weeks ago by  SirMaster.
    #19977

    Axelpowa (@axelpowa)
    Participant
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    Many many thanks for the advices!

    I’ll try as soon as I can.

    Regards!

    #19978

    SirMaster (@sirmasterboy)
    Participant
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    I will also add, you can try to do a BT2020 3D LUT for BT.2020 color profile mode on the projector, but you may find that you get posterization in the result.

    In that case, try making your 3D LUT for DCI-P3 color space. I looked at your projector and it seems that Cinema 2 is the color profile to use for DCI-P3 color space.

    It will then install the 3D LUT into madVR in the DCI-P3 slot and you do ont need to worry, madVR will remap the color points frm BT.2020 in the source video to DCI-P3 to be displayed to the projector’s DCI-P3 mode.

    Also, the projector does not exceed DCI-P3 color gamut anyways, so you are not losing any color gamut. Even though movies are mastered to BT.2020 color gamut, none so far use any colors outside the DCI-P3 gamut that I have heard of or seen.

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