Look at the picture. Watch the videotutorial. You can now do this, too.
Peter Drakulić writes:
In this tutorial we're going to learn how to setup and adjust a Defocus and a Mist effects,in compositor,using nodes.We're also going to learn how we could eliminate any artifacts caused by the Defocus node,using a very simple implementation ( used,in here,only for "still" renderings) of a technique that I,personally,call "3D Rotoscoping".
A more detailed tutorial on this technique is about to get published ,hopefully,soon,(I'm still experimenting...).