Patent ID: 7085403

Claim:
An automatic fingerprint identification method in which a fingerprint to be identified is matched against a template stored in memory, which method comprises a phase of coarse alignment, a phase of fine alignment, and a fingerprint matching phase in which parameters describing the matching are computed and used to make a decision about the fingerprint identification, wherein the fingerprint matching phase comprises: a step to select one ridge in the fingerprint examined and a counterpart for it in a template so that at least one of their endings meets the maximum distance condition, a step to cut the longer of one of the ridges matched to the length of the shorter one, a step to test whether the ridges matched can be made coincident by rotating one of the ridges by an angle smaller than a certain angle, a step to measure, point for point, the distance between corresponding points in the ridges, a step to test whether the point-to-point matching is in accordance with given limit values, a step to compute parameters describing the coincidence of ridges accepted as pairs and save the parameters computed, a step to check whether all possible ridge pairs have already been examined, a step to compute normalized parameters for the fingerprint examined on the basis of all ridge-specific comparisons executed, and a step to make a decision, based on the normalized parameters, as to whether or not the unknown fingerprint has been identified.