jibjab (insert your own face) implementation in Unity

I need to allow a users to create themselves as a game character. Are there any solid examples/apis on cropping a portion of an image and super imposing it on another image? #1 crop face (zoom original photo to size of cropping shape) from photos in device gallery #2 position face on character model #3 save image as the same resolution/quality to game cache (not photo gallery)