Fingerprints can be captured as graphical ridge and valley patterns. Because of their uniqueness and permanence, fingerprints emerged as the most widely used biometric identifier in the 2000s. Automated fingerprint verification systems were developed to meet the needs of law enforcement and their use became more widespread in civilian applications. Despite being deployed more widely, reliable automated fingerprint verification remained a challenge and was extensively researched in the context of pattern recognition and image processing.
The uniqueness of a fingerprint can be established by the overall pattern of ridges and valleys, or the logical ridge discontinuities known as minutiae. In the 2000s minutiae features were considered the most discriminating and reliable feature of a fingerprint. Therefore, the recognition of minutiae features became the most common basis for automated fingerprint verification. The most widely used minutiae features used for automated fingerprint verification were the ridge ending and the ridge bifurcation.
The three basic patterns of fingerprint ridges are the arch, loop, and whorl:
Arch: The ridges enter from one side of the finger, rise in the center forming an arc, and then exit the other side of the finger.
Loop: The ridges enter from one side of a finger, form a curve, and then exit on that same side.
Whorl: Ridges form circularly around a central point on the finger.
Scientists have found that family members often share the same general fingerprint patterns, leading to the belief that these patterns are inherited.