Fingerprint Analysis and Representation

A fingerprint is the reproduction of the exterior appearance of the fingertip epidermis. The most evident structural characteristic of a fingerprint is a pattern of interleaved ridges and valleys (Ashbaugh, 1999); in a fingerprint image, ridges (also called ridge lines) are dark whereas valleys are bright (see Figure 3.1). Ridges vary in width from 100 μm, for very thin ridges, to 300 μm for thick ridges. Generally, the period of a ridge/valley cycle is about 500 μm. Most injuries to a finger such as superficial burns, abrasions, or cuts do not affect the underlying ridge structure, and the original pattern is duplicated in any new skin that grows.