Study On Fingerprint Image Processing And Matching

Traditional security system is mainly based on token or password. With the development of society, this system has become vulnerable. To deal with this challenge, people have turned to the biometrics to improve identity verification by using his physical feature and behavior.A fingerprint is the pattern of ridges and valleys on the surface of a fingertip. Modern anatomy and statistics have proved that each individual has unique fingerprints and fingerprint doesn't change all life, i. e. fingerprint is steady and exclusive. As a primary biometric, fingerprint has been widely used in forensic, police and other security system and been studied by using pattern recognition technique firstly. Fingerprint identification has been synonymous with biometrics in many situations.Automatic fingerprint identification system (AFIS) has integrated image processing, pattern recognition and database technique. After 40 years of development from1960's, AFIS has been successful and still the hotspot in pattern recognition domain.Due to the problems in the acquirement, enhancement, character describing and matching, this dissertation is concentrated on two aspects, enhancement and matching. Much work has been done on the key information aquirment and correction, image filtering, feature matching. Experiment and evaluation of the whole algorithm are given.1. In this dissertation, a fingerprint orientation correction based on the optical model residual error is purposed. The noise can be separated from the topology structure of the fingerprint and be removed. Compared with the orientation low pass filtering usually used, our algorithm performance is better in the noise resistance.2. A frequency estimation via improved local Discrete Fourier Transformation and its'verification are proposed. The estimation can be applied on the small scale window with high accuracy. So it is with distinct advantage versus general projective method or the Fast Fourier Transformation. In addition, the fingerprint image quality is evaluated from the value of the master frequency amplitude as the basis of the quality-adaptive filtering.3. A quality-adaptive enhancement is presented. First the filtering intensity of the...