Lock control system based on face identification

Reliable and feasible security systems are needed at limited-access entrances. We have made an experimental lock-control system that unlocks the door when the system identifies a registered person's face. The face identification procedure was designed for practical use. There are three main processes in the face identification: 1) extraction of the face, 2) normalization of the size and inclination of the face image, and 3) matching of facial features (eye, nose, and mouth). In order to achieve high reliability, the normalization process uses inner corners of eyes as reference points for affine transformation. Matching is performed on the characteristic facial features (eye, nose, and mouth) for exclusion of features that are easy to imitate, such as eyeglass frames and hairstyle. Thresholds for the matching are determined by statistical estimation. In experiments, the system realized a correct acceptance rate of 92.2% and a correct rejection rate of 99.6%.