A camera is used to acquire image of face from a distance of a few feet. The system then analyzes particular features or discreet areas of the face such as the distance between the eyes and the nose and the shape and location of the cheekbones.
Most systems feature a face locating function that searches for faces within the field of view.
Facial scan systems are designed to compensate for glasses, hats and beards. The technology can perform verification and identification. Anecdotal evidence suggests that facial scan technology has the capability to be very accurate. The leading facial scan vendors are Visionics, Miros and Viisage. There are a number of identification applications with facial scan, including driver's license in Illinois, welfare fraud in Massachusetts, and INS pilots.