5 Replies Latest reply on May 15, 2008 5:19 PM by (Mark_Weiss)

    General chromakey help.  Lots of noise and magenta cast.

    Navarro Parker Level 3
      I'm having difficulties keying an evenly lit, Rosco chroma-green painted scene. I'm trying both Keylight and Primatte (not at the same time of course), but not getting satisfactory results. After appling the key, my non-keyed areas becomes incredibly noisy with a distinct magenta cast.

      Any suggestions?
        • 1. Re: General chromakey help.  Lots of noise and magenta cast.
          Mylenium Most Valuable Participant
          What's the source footage? Project bit depth? These issues are very specific and the only times I've heard of them were with some odd P2 footage and an older version of the Cineform CoDecs. In the latter case getting a newer version of the CoDec and working in 16bpc fixed the issue. I'd also look into your footage interpretation, maybe some odd color profile thing is skewing your colors and then the keyer can't make sense of them anymore.

          Mylenium
          • 2. Re: General chromakey help.  Lots of noise and magenta cast.
            Navarro Parker Level 3
            It's XDCAM EX footage (1080p, 35Mb VBR). 8-bit depth. But this is not specific to this format. I'm having the same trouble with DV and DVCPRO HD.
            • 3. Re: General chromakey help.  Lots of noise and magenta cast.
              Mylenium Most Valuable Participant
              Mmh, strange. The colors being so odd is easily explicable by a component shift in YUV space, but it's not clear why, as AE should properly expand the chroma subsampling to full RGB so it's probably already going wrong there somewhere. Do you use any of the deartifacting features in Primatte? During testing these were often a great source of confusion... Other than that you should be able to get easily a clean key. Trust me, I've thrown my cheap home HDV stuff at it and it always worked almost imemdiately even on poorly lit setups. The only other thing I can think of is that the colro temperature of the camera was completely wrong and the colors are all crooked and/or there is some color bleed from somewhere that throws the keyer off track... Really weird, this one.

              Mylenium
              • 4. Re: General chromakey help.  Lots of noise and magenta cast.
                Andrew Yoole MVP & Adobe Community Professional
                Try converting a small section of the footage to uncompressed and apply the keyer to the resulting file. If this eliminates the problem. it's almost certainly a computational error with the codec you're using. If the problem persists... not sure.

                Be sure you've downloaded the current versions of both plugins. Keylight has been updated since the release of CS3, for example.
                • 5. Re: General chromakey help.  Lots of noise and magenta cast.
                  Level 1
                  For one thing, AE does not support XDCam EX (at least not yet). That said, if you are able to get some of the footage into AE, simply drag the Keylight filter onto the EX1 footage, then click the eyedropper tool and click the background green screen. For me, that's all I have to do to produce a perfect key.
                  It sounds like you've twiddled a lot of other settings until the keyer was so badly twisted up that values for colors, despill, etc, were way out of range.
                  Keylight will pull a perfect key with XDCam footage with just one click. And I did mine with a piece of green fabric bought at a fabric store.