An Approach to Fingerprint Filter Design

A procedure for filter design is described for enhancing fingerprint images. The procedure consists of 5 main steps: user-specification of appropriate image features, determination of local ridge orientations throughout the image, smoothing of this orientation image, pixel-by-pixel image enhancement by application of oriented, matched filter masks, and post-processing to reduce background and boundary noise. The contribution of this work is to quantify and justify the functional relationships between image features and filter parameters so that the design process can be easily modified for different conditions of noise and scale. Application to different fingerprint images shows good ridge separation and continuity, and background noise reduction.