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  • P4K to Alexa Conversion

    "Pocket 4K footage is precisely transformed to match the color science of the Arri Alexa, without compromise. This is achieved without artifacts, while introducing a smooth, organic rolloff."

    For the better part of the last year, I've been working to map the color of P4K BMDFilm to match my Alexa's LogC, as measured under sunlight and halogen. To do this, I wrote an interpolation program in C++ that can accept an enormous amount of data (~40k samples per camera), and interpolate smooth internal contours, or 'waves' between them. Exposure compensation conversions were made with the same interpolation engine (transforms replicating sensor color response with variant exposure).

    Another significant element of the project was to recreate Arri's Rec709 to maintain the entirety of recorded LogC gamut, in a film-derived envelope (for the display variations). This was particularly difficult, as the correct RGB primary behavior needed to be exactly replicated within contiguous 709, but smoothly diverge to HDR-like handling of far gamut (where Arri's Rec709 ends). This new envelope (EC Gen.4) is particularly impressive, and I may release it for the Arri, as it is significantly preferable to normal Arri Rec709.

    P4Ka PDF

    Emotive Color





    Last edited by Sage; 11-25-2019, 06:43 AM.

  • #2
    Amazing work, Alex! Truly stunning results.

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    • #3
      Originally posted by jeremydulac View Post
      Amazing work, Alex! Truly stunning results.
      Thanks so much Jeremy!

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      • #4
        Looks great . Just need this for the UMP/g2 also. I use the g2 and p4k as A/B cam.
        Last edited by jambredz; 11-25-2019, 09:30 AM.
        Darren Scott
        Freelance Director/Director of Photography


        https://vimeo.com/jambredzvisions/videos

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        • #5
          That is an impressive secret sauce you have going there. Have you tried a contrast filter in the image path? The pocket image looks that little bit hotter in the highlights or maybe it was a slightly different lighting circumstance between shots.

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          • #6
            Wow, this looks great. Can't really argue with your results. Looking forward to playing with this.

            That's an interesting technique you used to match. Is this something new in this kind of field?

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            • #7
              Originally posted by jambredz View Post
              Looks great . Just need this for the UMP/g2 also. I use the g2 and p4k as A/B cam.
              Thank you Jambredz, I'd love to do that - Alas, each camera takes a while. I hope I can be more efficient next year

              Originally posted by Robert Hart View Post
              That is an impressive secret sauce you have going there. Have you tried a contrast filter in the image path? The pocket image looks that little bit hotter in the highlights or maybe it was a slightly different lighting circumstance between shots.
              Thank you Robert! I'm a big fan of LC filters. For this, it was just a plain APO 32mm Hyperprime, swapped on both cameras. Even under reference light, there will be slight variance

              Originally posted by TravisA View Post
              Wow, this looks great. Can't really argue with your results. Looking forward to playing with this.

              That's an interesting technique you used to match. Is this something new in this kind of field?
              Thank you so much Jeremy! It is quite rare - there is at least one other case:
              http://www.yedlin.net/OnColorScience/

              Comment


              • #8
                Originally posted by Sage View Post
                Thank you Robert! I'm a big fan of LC filters. For this, it was just a plain APO 32mm Hyperprime, swapped on both cameras. Even under reference light, there will be slight variance

                SLR magic APO Hyperprime?
                Darren Scott
                Freelance Director/Director of Photography


                https://vimeo.com/jambredzvisions/videos

                Comment


                • #9
                  Originally posted by jambredz View Post
                  SLR magic APO Hyperprime?
                  Indeed - its quickly becoming my favorite lens (the texture is amazing), and its my favorite focal length on S35

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                  • #10
                    Originally posted by Sage View Post
                    Indeed - its quickly becoming my favorite lens (the texture is amazing), and its my favorite focal length on S35
                    I have the full set. For the price they are some amazing lenses.
                    Darren Scott
                    Freelance Director/Director of Photography


                    https://vimeo.com/jambredzvisions/videos

                    Comment


                    • #11
                      this is awesome work!

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                      • #12
                        This sure is awesome work and thank you for doing so.

                        I always think colors and color grading is subjective to the creator and not the kind of camera or what the camera produces. That's the reason I shoot raw. I shoot raw regardless of camera, be it a BMPCC or an Alexa. I don't think of a BM extended color or an Alexa C-log color. They are irrelevant. I see colors the way I want to perceive the style and emotion that is for me. So I really don't care for a workflow. To me, get the exposure right then paint the hell out of it that makes me feel happy.

                        Then there are those who would prefer to endlessly debate matching colors of one camera to another. That's fine but artistically I just don't think it is necessary to make them match.

                        If I want to start with a base from different cameras, then I transform everyone of them to a common color space and gamma, say C-Log or whatever I think will be a good starting point. The I don't think about matching... as I said, just color the hell out of them to goodness.

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                        • #13
                          +1
                          The Blackmagic Design Cinema Camera - what it says on the box!

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                          • #14
                            Originally posted by jambredz View Post
                            I have the full set. For the price they are some amazing lenses.
                            Wow, I'd like to get the 85 especially

                            RomanStone, thanks so much!

                            Eyu, thank you! That's true. Its an art in the end, and I've seen amazing work from even the roughest camera bases

                            Comment


                            • #15
                              Any plans for an Ursa Mini LUT?

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