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How Do I properly use the BMD Extended LUT?

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  • How Do I properly use the BMD Extended LUT?

    I'm a bit confused right now. Can someone explain, why I'm getting two different images when using these workflows?
    I'm pretty sure, they should look the same.

    In A, I'm converting BMD FILM to REC709 with a LUT.
    In B, I'm only using the RAW settings to convert to REC709.

    A
    WORKING WITH LUT:

    BRAW set to
    COLOR SPACE: Blackmagic Design
    GAMMA: Blackmagic Design Film

    LUT: Blackmagic Pocket 4K Film to Extended Video v4


    B
    ONLY RAW SETTINGS:

    BRAW set to
    COLOR SPACE: Rec. 709
    GAMMA: Blackmagic Design Extended Video



    Left B, Right A
    Last edited by weui; 05-30-2019, 05:27 AM.

  • #2
    Luts in general can be destructive to your footage. Stick with the raw tab.

    The raw tab and the project settings are interchangeable. If you have project colorspace set to rec709, which is default, putting a lut on a node means you have it happening twice to the footage.

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    • #3
      Are you sure you didn't reverse it -- "A" being extended video in the raw tab, and "B" representing the extended video LUT?

      Note that when you set the gamma to BMPCC 4K extended video in the raw tab, the raw gamma controls, including contrast and saturation, get boosted above 1.0. That boost accounts for difference. Set the controls back to their defaults, and you should get the same result using either method.

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      • #4
        Originally posted by jrd View Post
        Are you sure you didn't reverse it -- "A" being extended video in the raw tab, and "B" representing the extended video LUT?

        Note that when you set the gamma to BMPCC 4K extended video in the raw tab, the raw gamma controls, including contrast and saturation, get boosted above 1.0. That boost accounts for difference. Set the controls back to their defaults, and you should get the same result using either method.
        You're right! A and B were reversed.
        Didn't notice the gamma controls changing before, thanks!
        But still, resetting them, makes the "only raw" settings flatter than the LUT version.
        I can only make them 99,5% the same, when I change the color space to Blackmagic Design, instead of Rec709 in the Raw version.
        This makes me assume that the LUT is in fact not doing color space "conversion" from Blackmagic Design -> Rec709.

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        • #5
          Extended Video is not Rec709 and not intended to be. It does not clip any highlights unlike Rec709 and the gamut is in general wider than 709 to allow you some room to make more adjustments if necessary.

          In the Blackmagic RAW tab you leave the colour space as Blackmagic Design and set the gamma to Extended Video - this will change the saturation amount (and the other controls) in the custom gamma controls to the appropriate amount for the camera the clip came from for it to be Extended Video. This would match closely to the Extended Video 3DLUT (make sure you use tetrahedral interpolation in your Resolve project settings for 3DLUTs).

          If you set the controls back to defaults it is no longer Extended Video and you will notice if you change the custom gamma controls from Extended Video the gamma dropdown menu will automatically change to "custom" since you are now creating your own custom gamma.
          Blackmagic Design
          My BMD LUTs.

          **Any post by me prior to Aug 2014 was before i started working for Blackmagic**

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          • #6
            Originally posted by CaptainHook View Post
            Extended Video is not Rec709 and not intended to be. It does not clip any highlights unlike Rec709 and the gamut is in general wider than 709 to allow you some room to make more adjustments if necessary.

            In the Blackmagic RAW tab you leave the colour space as Blackmagic Design and set the gamma to Extended Video - this will change the saturation amount (and the other controls) in the custom gamma controls to the appropriate amount for the camera the clip came from for it to be Extended Video. This would match closely to the Extended Video 3DLUT (make sure you use tetrahedral interpolation in your Resolve project settings for 3DLUTs).

            If you set the controls back to defaults it is no longer Extended Video and you will notice if you change the custom gamma controls from Extended Video the gamma dropdown menu will automatically change to "custom" since you are now creating your own custom gamma.
            Awesome, thanks for clearing this up!

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