I'm a compositor (Visual effects artist), I can combine CG with live action scene by using my skills in Tracking, matte painting, color matching, chroma keying and other techniques. with more simple words.. I can add some visual effects to the scene like smoke, rain, fire, etc. I can edit and retouch your footage like removing or adding an object to your footage or retouch the skin of somebody at your footage like the face skin or changing the texture of a wall or a book or whatever, etc.