Big-budget special effects could soon be within the grasp of low-budget film-makers thanks to a new technique for automatically replacing one actor's face with another's.
Face replacement is a much-used effect in Hollywood productions, even cropping up in realistic drama films such as The Social Network, in which two unrelated actors played a pair of twins. The complex and expensive equipment it requires, not to mention dedicated visual effects artists, have kept it out of low-budget movies, though.
No longer. "We achieve high-quality results with just a single camera and simple lighting set-up," says Kevin Dale, a computer scientist at Harvard University who came up with the new technique.
Dale and colleagues start a face "transplant" with an algorithm that creates 3D models of each face. Their system then automatically morphs the image of the donor's face to match the recipient, but that alone doesn't create a realistic-looking video – a joining seam is visible. "One frame might look good, or many frames in sequence might look good individually, but when you play them together you get flickering," explains Dale
In addition to performing face transplants, Dale says directors could also use his system to blend multiple versions of an actor's performance into a single scene. It can combine the mouth from one take with the eyes from another, for example, because it can match slight differences in movement between two videos. It can't handle every situation, however, and videos with complex or very different lighting won't match up well.