Question about pixel

Hello, everyone.
I'm new here. Now I want to create a project with MAX and Kinect. It will make a person into pixels. But the question is, I want to remember the position of every pixel so that I can do something with them. For example, I color one of the pixels of the shoulder in red, no matter how I move, the red pixel is always at that position.
I want to know, is that possible for me to do this? If I raise my arm, not only the shape, also the number of the pixels will change. Is there any methods for me to do this?
Thanks.