Patent ID: 7856127

Claim:
A ridge direction extraction device comprising: a zone direction extractor which divides an input fingerprint image into a plurality of zones, and calculates a ridge direction and confidence of the ridge direction for each of the plurality of zones; a high confidence zone area determiner which determines a high confidence zone area based on the confidence of the ridge direction for each of the plurality of zones calculated by the zone direction extractor, and determines a plurality of propagation candidate zones around the high confidence zone area; a direction expectation calculator which determines a first plurality of reference zones for a first propagation candidate zone from among the plurality of propagation candidate zones by searching a plurality of search directions around the first propagation candidate zone, calculates inner angle weighting and direction weighting contributions of each of the first plurality of reference zones, calculates weighting contribution for each ridge direction by summing the direction weighting contribution for each ridge direction of the first plurality of reference zones, and calculates direction expectation for each ridge direction based on a ratio between the weighting contribution for each ridge direction and an average thereof; and a propagation zone direction extractor which recalculates direction confidence of ridge direction for the first propagation candidate zone based on the direction expectation calculated by the direction expectation calculator, and determines a direction of the first propagation candidate zone based on the recalculated direction confidence.