I am currently editing a clip in After Effects. We had a very limited supply of green screen so I am now having to edit some of the white wall too. The thing is, the actors move around, not allowing me to clip out these parts.

I was wondering if there was a thing in After Effects that allowed me to break up the clips so that I can work around the actors in certain time intervals and get the white wall to be transparent.


  • There's no easy way. Luma key on the white walls, and roto any trouble spots.
    – datageist
    Feb 7, 2012 at 14:38

2 Answers 2


I hope I understand this correctly, are you saying that you have actors in front of a green screen and sometimes they are off the screen? If you want to chroma key the green screen to be another surface you have to have it consistent all the way through. Green screen is hard enough to get right. (Green or blue screen backgrounds have to be evenly lit with a flat diffused light, non-reflective, and no shadows, otherwise the green screen will look blotchy, and have noise areas that you can't just tweak out.)

Trying to mask out where your actors fall out of the green screen frame does not have a solution in it. If you didn't get this right in production you won't be able to fix this in post. At least not fix it in post with anything that looks close to natural. I highly recommend you shoot this over.

  • It is fixable in post, though it's more work. And as mentioned in my answer there is a tool for exactly this job.
    – stib
    Jan 14, 2015 at 14:14

Have you used the Roto Brush? It was designed for situations like these.

For those unfamiliar, there is a nice concise tutorial here on how to use the Roto Brush.

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