Face recognition is considered as one of the most difficult research topic in the fields of biometric features recognition and even artificial intelligence. The difficulties of face recognition mainly is because face is as the biological characteristic.
All of our faces are similar, there is a little differences among the different body, even the appearance and structure of human face are both similar. This characteristic is advantage for locating with human faces, but is disadvantage for distinguish the human body with the face.
The appearance of human faces is not the same, we can generate many expressions through the change of faces, and the visual pattern of the human faces is have a big different if we at different angles of view, and it is also affected by the light condition, covering and age.
Face recognition is mainly used for identification. Since video surveillance is rapidly spreading, many video surveillance applications urgently need a fast identification technology in a long-distance and user-incompatible state, in order to quickly confirm the identity of a person at a long distance and realize intelligent early warning. Face recognition technology is undoubtedly the best choice. Fast face detection technology can be used to find faces in real time from surveillance video images and compare them with face database in real time to achieve fast identification.