Facial recognition system introduced varying technologies to the procedure. Some of the most notable include the following techniques: Some face recognition algorithms identify facial features by extracting landmarks, or features, from an image of the subject's face. For example, an algorithm may analyze the relative position, size, and/or shape of the eyes, nose, cheekbones, and jaw. These features are then used to search for other images with matching features. Other algorithms normalize a gallery of face images and then compress the face data, only saving the data in the image that is useful for face recognition. A probe image is then compared with
Facial composite called "Identikit", was introduced in the U.S. in 1959; it used drawings of facial features on transparent acetate sheets that could be superimposed on one another to produce the composite image. (A later version of Identikit is made by Smith & Wesson.) In 1970, a system called "Photofit", which aimed for greater realism by using actual photographs of facial features, was introduced in the U.K. In the last two decades, a number of computer based facial composite systems have been introduced; amongst the most widely used systems are SketchCop FACETTE Face Design System Software, "Identi-Kit 2000", FACES, E-FIT and PortraitPad.