5 Replies Latest reply: Dec 1, 2009 11:11 AM by Lars Borg RSS

    CinemaDNG DI?

    cmdurham Community Member

      Anyone know if there are any film scanners in the works that might encode to DNG. I can't say as there would be an inherent advantage to DNG over other DI formats, although raw manipulations of the file could be a lot more efficient than re-encoding DPX's for instance. But really what I'm interested in is that if I have a CinemaDNG workflow and decide to use film, I don't have to change a thing once I scan the film.

        • 1. Re: CinemaDNG DI?
          Lars Borg

          Don't know of any film scanners with DNG support yet.

          Is there a vendor you think we should approach?

           

          A film scan could be stored in DNG. Preferably you would use 10-bit

          log encoding of RGB, just as in DPX. You also would need to store the

          proper parameters: an anti-log decoding table, a matrix to XYZ.

           

          Note though, that the DNG color management is designed for digital

          capture, not film. The interimage effect of film is not handled in

          the simplest DNG color management use  case, so it won't restore the

          correct scene colorimetry (which is what you want for VFX). Of

          course, you may be fine working in linear RGB regardless of color

          management.

           

          Lars

          • 2. Re: CinemaDNG DI?
            unbunt

            hi lars,

             

            we are a small company which develop a 2k filmscanner for 16mm and 35mm film. after i heard from iridas that they support DNG in speedgrade i thought this could be a nice feature to store directly dng with our scanner. we are using a 1 chip ccd 2k camera and so we could easy implement dng. can you give us more details to make a decission if it is really a good idea to work with dng as DI?

             

            with kind regards

            rudi

            • 3. Re: CinemaDNG DI?
              cmdurham Community Member

              What exactly do you mean by "using a 1 chip ccd 2k camera ?" That sounds more like a telecine than a film scan. Maybe I'm misunderstanding. Are you perhaps using a camera's sensor to do the scanning.

              • 4. Re: CinemaDNG DI?
                cmdurham Community Member

                Lars, I'm certainly not an engineer so I'm not sure what takes place in the raw file. I obviously can't scan more detail than is present in the image being scanned; however when I shoot a still with my DSLR and store it as raw, I can then take it into the digital dark room and pull more detail than is immediately visible. I can pull the exposure slider down a stop or two and highlights which seemed blown out now have detail. In film terms, I'm "printing down." The same thing takes place in the raw files coming off a Red camera - a user can alter the exposure by changing the ISO in post. This is the kind of thing I'd like to be able to do with a film scan. Perhaps it requires more than a 10-bit log file to do so. Maybe it needs to be 16-bit linear to capture more detail than is immediately visible in order for an operator to bring that detail into visible space. After all I assume that you would want linear data to which you would apply a logarithmic LUT for post processing and eventual output to DPX or whatever.

                 

                Again, I'm not an engineer, so some of what I'm thinking may be incorrect; but my ultimate goal would be a fully raw workflow even if I had film origination.

                • 5. Re: CinemaDNG DI?
                  Lars Borg Community Member

                  cmdurham,

                   

                  Yes, you can store a film scan in DNG format. Note that the raw film

                  scan is always log encoded, as the film has a log response to light,

                  so the DNG file will be log encoded as well. The film's response

                  usually helps you preserve detail in the highlights.

                  A typical DPX file stores 10 bits per channel, while DNG often stores

                  more, depending on your camera sensor. Don't know if those extra bits

                  help much, though.

                   

                  Lars