Can I create my own Green Screen effect in Pixelmator?

[Sandee]

Hi!

I'm not even sure this can be done. But somehow it seems to me that it might be possible. Please excuse me if I'm not explaining this correctly...I'm still fairly new at all this - esp. Pixelmator!

I don't have the capability to shoot a scene using a green screen. Is it at all possible to create a green screen in Pixelmator instead? Here's a scenario:

I want a picture of an audience facing toward me that I can put a performer in front of. So the audience is seeing the front of the performer but the viewer is seeing the back of the performer and the faces of the audience. I found one that could work. But it has a white background. I would like to replace that white background with a green background...which to me in my mind could effectively create a green screen that can then be keyed out in Final Cut.

Is my thinking completely flawed? Thank you for your help and explanations!!