You could start by checking out the user media object, which references the use of the camera.
From there you should be able to manipulate the current pic etc.
I have not used it myself extensively, so I am not aware whatt he manipulating options are.
But if there arent any, I would imagine performing some sort of effects as an overlay over the image, and create a snapshot from that.
There is a tutorial somewhere which references to uploading images to a server with PHP.