I got a project but before to start the work on it , I want to clear some questions.

Actually want to do a chroma keying effect. But I have some questions about it.

First of all there is live video feed and from there I want to track color(i.e solid blue or green). I also track the color but what to do after this " how to remove that color and place the other graphics "that's my question.

B'coz , if the color is detected then I want to remove that color and place a graphic (e.g some animation). Also this animation would get the users faces. So how to merge the faces with animation that is my second question. 

Some thing   like this

Any help would br greatly appreciated...

Thanks in Advance...