Ear Biometrics in Passive Human Identification Systems

The article discusses various issues concerning ear biometrics in human identification systems. The major advantage of ear as the source of data for human identification, is the ease of image acquisition, which can be performed even without examined person’s knowledge. Moreover, user’s acceptability and easy interaction with the system make ear biometrics a perfect solution for secure authentication e.g. in access-control applications. In the article the focus is on the ear biometrics motivation, ear identification system design and interaction with the user. Feature extraction methods from ear images are also discussed. 1 Motivation for Passive Human Identification Systems Biometrics methods of human identification have gained much attention recently, mainly because they easily deal with most problems of traditional identification, since users are identified by who they are, not by something they have to remember or carry with them. The passive methods of biometrics do not require any action from users. Some systems can even verify the identity of humans without their cooperation and knowledge, which is actually the future of biometrics. Crowd-surveillance, monitoring of public places like airports or sports arenas are the most important applications that need such solutions. Possible passive methods include popular and well-examined face recognition, but one of the most interesting novel approaches to human passive identification is the use of ear as the source of data. The most interesting human anatomical parts for passive, physiological biometrics systems based on images acquired from cameras are face and ear. Both of those body parts contain large volume of unique features that allow to distinctively identify many users and can be implemented into efficient biometrics systems for many applications. However, still the automated system of ear recognition has not been commercially implemented, even though there are many advantages of using ear as a source of data for person identification (small size, stable features, uniform colours). Furthermore, ear is one of our sensors, therefore it is usually visible (not hidden underneath anything) to enable good hearing. In the process of acquisition, in contrast to face identification systems, ear images cannot be disturbed by glasses, beard or make-up. However, occlusion by hair or earrings is possible, but in access control applications, making ear visible is not a problem for user and takes just single seconds (Fig. 1).