"When I woke up, and I was able to feel I had features again -- eyes and a noseand a mouth -- I even said out loud that this could not be medically possible, " Wiens said Monday.
Today's facial-recognition systems use a camera to zoom in on an individual's eyes, mouth andnose, and extract a "feature vector, " a set of numbers that describes key aspects of the image, such as the precise distance between the eyes. (Remember, in the end, digital images are just numbers.) Those numbers can be fed back into a large database of faces in search of a match.