Two-stage local and global fingerprint matching technique for automated fingerprint verification/identification

Abstract

A method for determining a degree of match between a search fingerprint and a reference fingerprint comprises the following: a) Extracting at least one first search feature from a first region of said search fingerprint thereby forming a local search feature vector, b) Extracting at least one second search feature from a second region of said search fingerprint thereby forming a global search feature vector, whereby said second region comprises said first region, c) Determining a first similarity degree by comparing said local search feature vector with a local reference feature vector, d) 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, e) 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.

What is claimed is:  
     
         1 . A method for determining a degree of match between a search fingerprint and a reference fingerprint comprising: 
 a) Extracting at least one first search feature from a first region of said search fingerprint thereby forming a local search feature vector,    b) 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,    c) Determining a first similarity degree by comparing said local search feature vector with a local reference feature vector of said reference fingerprint,    d) 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,    e) Determining said degree of match from said second similarity degree, wherein said feature vectors describe at least one of minutiae of said fingerprints and a relation between minutiae of said fingerprints.    
     
     
         2 . A method according to  claim 1 , 
 wherein said features are independent from at least one of rotation and translation of the fingerprints compared with a given coordinate system.    
     
     
         3 . A method according to  claim 1 , wherein 
 said first region comprises a given first amount of neighbor minutiae;    said second region comprises a given second amount of neighbor minutiae; and    said second amount is larger than said first amount.    
     
     
         4 . A method according to  claim 1 , further comprising: 
 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; and    Aligning all minutiae in said second region based on said best match local structure pair, thereby forming said global search feature vector.    
     
     
         5 . A device for determining a degree of match between a search fingerprint and a reference fingerprint comprising: 
 a) Means for extracting at least one first search feature from a first region of said search fingerprint thereby forming a local search feature vector,    b) Means for 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,    c) Means for determining a first similarity degree by comparing said local search feature vector with a local reference feature vector of said reference fingerprint,    d) Means for 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,    e) Means for determining said degree of match from said second similarity degree, wherein said feature vectors describe at least one of minutiae of said fingerprints and a relation between minutiae of said fingerprints.    
     
     
         6 . A computer readable medium having a program recorded thereon, wherein the program is to make a computer execute a procedure for determining a degree of match between a search fingerprint and a reference fingerprint, the procedure comprising instructions for the steps of: 
 a) Extracting at least one first search feature from a first region of said search fingerprint thereby forming a local search feature vector,    b) 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,    c) Determining a first similarity degree by comparing said local search feature vector with a local reference feature vector of said reference fingerprint,    d) 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, and    e) Determining said degree of match from said second similarity degree, wherein said feature vectors describe at least one of minutiae of said fingerprints and a relation between minutiae of said fingerprints.    
     
     
         7 . A computer program for determining a degree of match between a search fingerprint and a reference fingerprint, the program comprising instructions for: 
 a) Extracting at least one first search feature from a first region of said search fingerprint thereby forming a local search feature vector,    b) 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,    c) Determining a first similarity degree by comparing said local search feature vector with a local reference feature vector of said reference fingerprint,    d) 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, and    e) Determining said degree of match from said second similarity degree, wherein said feature vectors describe at least one of minutiae of said fingerprints and a relation between minutiae of said fingerprints.