9 Replies Latest reply on Oct 12, 2016 9:31 AM by Dave LaRonde

    Keying issue (green screen pixels)

    candacel81401869

      Hi,

       

      I am trying to key in a green screen background in After Effects.

       

      I have a video of three people sitting at a table in front of a green screen. When I key in the background and make adjustments to the Screen Grain, Screen Balance,Clip Black, and Clip White I still get a lot of noise pixelation and green in the shadows and dark spots under the table.  We shot in HD but are burning the final product to a standard definition disc. When the video is burned to the disc, the pixelation is really apparent and I don't know what else to do to get rid of it.

       

      If someone could please help me with this, I would really appreciate it.

        • 1. Re: Keying issue (green screen pixels)
          Roei Tzoref Adobe Community Professional
          We shot in HD but are burning the final product to a standard definition disc.

          Oy vey... can't you get the original footage? this is really important. resolution is not the only thing, it is also important to try and shoot with a good camera that uses no compression such as 4:4:4 meaning no chroma subsampling (like you will get with DSLR Cameras) but you make do with what you have...

           

          When I key in the background and make adjustments to the Screen Grain, Screen Balance,Clip Black, and Clip White I still get a lot of noise pixelation and green in the shadows and dark spots under the table. 

          this could be something that a proper workflow could fix. we need to see the footage in it's best quality even a few seconds so we can determined what can be done here.

          • 2. Re: Keying issue (green screen pixels)
            Dave LaRonde Level 6

            Got a screen shot of the problem key?  There are a LOT of variables that go into a good chroma key shot -- you can just throw up a background, switch on a couple of lights and expect immediate success.

            • 3. Re: Keying issue (green screen pixels)
              Mylenium Most Valuable Participant

              Nobody can tell you anything without seeing your shots and keyer settings. As the others already explained, there's a thousand things that influence the quality of a key and you are not giving us anything concrete to work with.

               

              Mylenium

              • 4. Re: Keying issue (green screen pixels)
                candacel81401869 Level 1

                Here is a screenshot of a video clip set to the status view.Green screen key shot.png

                I'm not sure how to get rid of the green parts. This is what shows up as pixelation and noise when we export the footage.

                • 5. Re: Keying issue (green screen pixels)
                  candacel81401869 Level 1

                  Here is a screenshot of a video clip set to the status view.Green screen key shot.png

                  I'm not sure how to get rid of the green parts. This is what shows up as pixelation and noise when we export the footage.

                   

                  • 6. Re: Keying issue (green screen pixels)
                    Mylenium Most Valuable Participant

                    You need to show us the unkeyed version as well. Apparently this is some sort of glass table an in that case it's probably a lot more complicated plus you seem to have an awful lot of green spill due to lack of separation between the screen and the foreground. This will be a tough one...

                     

                    Mylenium

                    • 7. Re: Keying issue (green screen pixels)
                      candacel81401869 Level 1

                      Here you go. It's a wooden table, but still kind of glossy.  They are seated pretty close to the green screen. unkeyed shot.png

                      • 8. Re: Keying issue (green screen pixels)
                        Dave LaRonde Level 6

                        Your best bet may be to break this shot up into sections.  This could be a real bear if there's camera movement, but you may not have much of a choice.

                        A possibly-animated mask for the tabletop

                        Below table & Screen Left Key

                        Above the table & Screen Center to Screen Right key

                         

                        Splitting up the screen into keying areas is due to the uneven lighting on the green screen; you'll notice that it's a darker green below the table & screen left -- for keying purposes, it's a different color!

                         

                        Once you have a good-looking key -- the edges are okay, the core is solid, don't worry about color variations -- you can then precomp those layers, and use the precomp as an Alpha Matte for the un-keyed footage to create the final key... which you can then color correct, if necessary.