Minutiae-based partial fingerprint recognition

Although fingerprint matching based on minutia features is a well researched problem in the field of automatic fingerprint recognition, it is still an unsolved problem presenting many research challenges. Many algorithms have been proposed to match a pair of minutia templates of fingerprints. Most of these algorithms assume that the two templates are approximately of the same size. This assumption is no longer valid. The need for recognition of partial fingerprints is increasing in both forensic and civilian applications. In forensics, latent fingerprints lifted from crime scenes are often noisy and broken, thus the usable portions are small and partial. In civilian applications, the invention of small hand-held devices, such as mobile phones, PDAs, and miniaturized fingerprint sensors present considerable demands on partial fingerprints processing. Miniaturization of fingerprint sensors has led to small sensing areas varying from 1.0"x1.0" to 0.42"x0.42". However, fingerprint scanners with a sensing area smaller than 1.0"x1.0", which is considered to be the average fingerprint size (as required by FBI specifications), can only capture partial fingerprints. Matching partial fingerprints against full pre-enrolled images in the database presents several problems: (i) the number of minutia points available in such partial fingerprints is few, thus reducing its discriminating power; (ii) loss of singular points (core and delta) is likely and therefore, a robust algorithm independent of these singularities is required; (iii) uncontrolled impression environments result in unspecified orientations of partial fingerprints; and (iv) the skin elasticity and humidity can cause distortions which increase the ambiguity between genuine and imposter samples. Generally, a fingerprint based biometrics system is considered as highly secure, and is equivalent to a long password system. However, with the decreasing number of features on a small fingerprint and the non-exact matching nature, the security strength of a partial fingerprint recognition reduces. The relation between the acquired fingerprint size and the security strength plays a key role in designing a fingerprint recognition system and is needed to be studied. In this dissertation, we present: (i) two novel minutiae based fingerprint matching methods to overcome the challenges encountered by partial fingerprint recognition and (ii) a study of the security vulnerability of partial fingerprint recognition systems.