5 Replies Latest reply on Mar 2, 2011 8:46 PM by Rick Gerard

    Arri Alexa ProRes 4444 LogC footage in AE CS5

    theiceage13 Level 1

      Hi,

       

      what is the correct workflow when dealing with LogC footage from the Alexa camera?

       

      For now I did the following:

       

      I turned on color management with Rec.709 working space.

       

      What is the correct interpretation for my footage? I choose "Universal Camera Film Printing Density" and that looks correct. But is it really correct? I've read in the Arri forums that their footage is not recorded in standard cineon, but SIMILAR to that. Does anyone have any experience on that?

       

      One other thing: When choosing "linearize workflow", my AJA Video Output is way too dark. My screens show the same picture like they do when I don't select "linearize" I understand the theory behind it and why it is too dar - but, is there any way to compensate for this on the video preview?

       

      Thanks!

        • 1. Re: Arri Alexa ProRes 4444 LogC footage in AE CS5
          theiceage13 Level 1

          I just noticed that in some shots my highlights are blown out. I have to assign a Levels-effect with "Output White" set to something 0,8 to get rid of the blown out highlights.

          • 2. Re: Arri Alexa ProRes 4444 LogC footage in AE CS5
            Bob Currier Level 3

            You can download appropriate viewing LUTs for Alexa LogC from Arri's web

            site. These can be applied to your footage using the LUT effect.

             

            LogC is its own unique curve and color space, so you need to use the

            right tools for it, not try to apply something built for other spaces.

            1 person found this helpful
            • 3. Re: Arri Alexa ProRes 4444 LogC footage in AE CS5
              theiceage13 Level 1

              Bob,

               

              nice! That seems to do the trick for me when viewing in AE. But here's the tricky part:

               

              I need to do my compositing mixing Alexa footage and other RGB-files. So - in the end I'm gonna need a logarithmic DPX-sequence for colorgrading in Autodesk Lustre. How do I render in Log? Deactivating the LUT effect on Alexa clips? But what about the RGB images? And what colorspace do I select in the output module? Do I need some kind of reverse-LUT for this? I don't know any place to provide a LUT for rendering.

               

              (argh...this stuff is confusing!)

              • 4. Re: Arri Alexa ProRes 4444 LogC footage in AE CS5
                Bob Currier Level 3

                If you've got a mix of formats, it's best to convert things into one

                common format. You can use a LUT to convert the Alexa footage from LogC

                to linear, then apply the Cineon effect to convert that linear to log

                and render the results out as log DPX.

                 

                Now everything is in log and you can composite and render to your

                heart's content. Or convert the Arri footage to Rec709, do your

                compositing in that space, then convert to log for your final DPX render.

                 

                But you'll want to do a lot of testing to make sure you're not losing

                color accuracy or clipping highlights with all that conversion. Working

                in Rec709 is easiest, but it's a more limiting color space.

                • 5. Re: Arri Alexa ProRes 4444 LogC footage in AE CS5
                  Rick Gerard Adobe Community Professional & MVP

                  You might want to visit the CineTechnica blog and read some of their articles on Log color. It's a good place to start. There are also many discussions on log color workflow on the Red forums.

                   

                  Then you'll want to work out a production workflow that fits your project and make sure that everyone from the DP to the final Color Grader is on board. It's critical to have all of this worked out before you start building things that fall apart downstream.