4 Replies Latest reply on Oct 5, 2015 10:43 AM by Dave LaRonde

    Chroma Key Problems - White Edges

    foreverahippy Level 1

      Hey guys.


      I'm trying to use Keylight in After Effects to pull a key from some footage I shot.

      I highly under-estimated the difficulty of pulling a good key.


      I don't feel like the green screen is that poorly lit, but I'm guessing it is or I wouldn't think I'd be having the problems I'm having.


      I used a technique I saw in a tutorial video that has you use the Selective Color effect in AE to make the green screen far more green before keying, but despite delivering on the promise of a far more green green-screen, it didn't seem to help the key.


      Anyhow, here's a screenshot from the original shot:

      green-screen-problems.png - Google Drive


      Here is a cropped screenshot of the problem I'm encountering... I can't get rid of much more of the white/gray edges without losing chunks of hair.

      green-screen-white-edges.PNG - Google Drive


      Obviously, it looks fantastic on a white background

      It even looks pretty good on any color except black.


      Any help would be greatly appreciated.


      Thanks for your time!

        • 1. Re: Chroma Key Problems - White Edges
          Mylenium Most Valuable Participant

          Looks like compression artifacts, which isn't really related to keying. You need to apply a de-blocking plug-in or use the respective manual techniques. The screen color is shifted into the blue, but should be perfectly keyable without oversaturating the color...



          • 2. Re: Chroma Key Problems - White Edges
            Rick Gerard Adobe Community Professional & MVP

            What Mylenium said was accurate. You need to reduce the edge artifacts and then use the edge cleaning tools in AE and in Keylight. Every time I'm faced with a shot that has this kind of trouble my first step is to make a 10 bit or better digital intermediate using a production codec or render the original video to a Tiff sequence, then do the rest of the processing on a file that has greater bit depth. You should be able to choke down and refine the edges enough to remove the edge artifacts but you are going to have to settle for losing a little edge detail also.


            In the future please drag your sample images into the Reply field on this forum instead of linking them to external hosts. I've almost completely stopped going to external URL's to look at things because if I don't know and can't verify a site I'm not going there ever...

            • 3. Re: Chroma Key Problems - White Edges
              foreverahippy Level 1

              Thank you both for your help.

              As recommended, I will drag the photos into the reply field from now on. Sorry about that
              Also, can either of you recommend a 'de-blocking plugin'?

              • 4. Re: Chroma Key Problems - White Edges
                Dave LaRonde Level 6

                I'd think AE's built-in Simple Choker or Matte Choker can do the trick.  So would the one in Keylight. When choking, using the bare minimum is best.