Patent ID: 6778685
Filing Date: 2004-08-17
Classification: G06K

Abstract:
A method for determining a degree of match between a search fingerprint and a reference fingerprint comprising the following steps:extracting at least one first search feature from a first region of said search fingerprint thereby forming a local search feature vector, extracting at least one second search feature from a second region of said search fingerprint thereby forming a global search feature vector, wherein said second region comprises said first region, determining a first similarity degree by comparing said local search feature vector with a local reference feature vector of said reference fingerprint, determining a second similarity degree by comparing said global search feature vector with a global reference feature vector of said reference fingerprint and using said first similarity degree; determining said degree of match from said second similarity degree, wherein said feature vectors describe minutiae of said fingerprints or a relation between minutiae of said fingerprints; and further comprising the steps of determining said first similarity degree for all minutiae in said first region, determining a best match local structure pair of minutiae by using said first similarity degrees, aligning all minutiae in said second region based on said best match local structure pair, thereby forming said global search feature vector; and wherein said first similarity degree cl(k1, k2) is determined using the following formula: c1&af;(k1,k2)={b1-WÃ—&LeftBracketingBar;FLk1S-FLk2R&RightBracketingBar;b1,if&it;â€ƒ&it;WÃ—&LeftBracketingBar;FLk1S-FLk2R&RightBracketingBar;<b10,Otherswhereinbl is a freely selectable local threshold, W is a freely selectable weight vector that specifies the weight associated with each component of said feature vector, FLk1S is a local search feature vector of minutia k1, FLk2R is a local reference feature vector of minutia k2.