A digital camera acquires an image of the face.
Software locates the face in the image, this is also called face detection. Face detection is one of the more difficult steps in face recognition, especially when using surveillance cameras for scanning an entire crowd of people.
When a face has been selected in the image, the software analyses the spatial geometry. The techniques used to extract identifying features of a face are vendor dependent. In general the software generates a template, this is a reduced set of data which uniquely identifies an individual based on the features of his face.
The generated template is then compared with a set of known templates in a database (identification) or with one specific template (authentication).
The software generates a score which indicates how well two templates match. It depends on the software how high a score must be for two templates to be considered as matching, for example an authentication application requires low FAR and thus the score must be high enough before templates can be declared as matching. In a surveillance application however you would not want to miss out on any fugitive criminals thus requiring a low FRR, so you would set a lower matching score and security agents will sort out the false positives.
APPLICATION OF FACE RECOGNITION
Face recognition can be used together with surveillance cameras to automatically identify missing children, unwanted subjects or criminals for which a picture is registered in a central database.
Different solutions exist for both small and large businesses, as well as for private use, that apply face recognition for access control to computer systems. Software requiring only a webcam to use face recognition instead of passwords to secure your computer or laptop is around for multiple years. Sensible Vision and Keylemon have developed software suitable for small companies and home users:
Sensible Vision has developed a face recognition software that uses such standard cameras to authenticate users on their computer. When an individual sits in front of the computer, the camera acquires an image which the software uses to identify the individual. If the individual in front of the computer is a registered user, then he will be automatically logged on to the computer. As soon as the individual leaves the computer, this is detected by the software and the user is logged off. We did not yet review this face recognition software.
A very similar software has been developed by KeyLemon, however we succeeded in hacking KeyLemon software easily even with its strongest security settings activated. Read our review of KeyLemon face recognition.
Furthermore a lot of system integrators develop custom solutions for border control and physical access control.