9.3: A Survey of Biometric Techniques

9.3 A Survey of Biometric Techniques

Many physical and behavioral traits are more or less suitable as a personal identifier. Physical identifiers tend to be relatively stable, although some are susceptible to aging, and they are often unalterable without the infliction of physical trauma. Behavioral characteristics, although having a physiological component, tend to vary more or less with a person's psychological state.

Contrary to behavioral characteristics, most physical characteristics are captured by optical sensor technology. In the majority of cases, the optics of biometric systems are relative simple, consisting of a light source, a positioning device for the biometric, and a CCD camera. Optical filters may further select specific spectral wavebands. In the case of finger and retinal patterns, the optics may be more complicated. Generally, the intricacy of biometric technology is based more on template conversion and comparison algorithms than on optical techniques.

It is not the purpose of this introductory chapter to discuss biometric techniques in detail. For detailed information, reference is made to review articles [16 26], the magazine Biometric Technology Today [27], biometric reports [6, 28], books [16, 29], and the Web sites of the Biometric Consortium [30], the Association for Biometrics [31], the International Biometrics Industry Association [32], Avanti [33], and the website of the International Biometric Foundation. ^[3]

An overview of various biometric techniques is given in Table 9.2. Some of these techniques are still in their infancy; others are past the age of childhood and find successful commercial application. Note that a distinction...