Method and apparatus for fingerprint characterization and recognition using auto correlation pattern
AssigneeThorn EMI plc
InventorAlastair Sibbald
Life of this patent
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Abstract
Apparatus for use with an autocorrelation technique for characterizing fingerprints includes an imaging device for providing an image of a fingerprint. The image so produced is then utilized by a microprocessor in order to generate an autocorrelation pattern for statistical comparison with stored data so as to determine whether the image of the fingerprint under test is derived from the fingerprint representated by the stored data.
Claims18
An apparatus for characterizing an image of a fingerprint under test to determine if the fingerprint under test matches a previously characterized fingerprint, the apparatus comprising:
- a fingerprint image capturing means for generating an image of the fingerprint under test comprising a receiving surface adapted to receive a surface of a finger bearing the fingerprint under test and an illumination device for illuminating said surface;
- transducer means optically connected to said capturing means for receiving said image and for generating electrical signals representative of said image in response thereto;
- storage means, connected to said transducer means, for storing said electrical signals as a binary image of the fingerprint;
- replicating means for producing a replica of the binary image;
- combining means for effectively overlying the replica on the binary image and generating an autocorrelation pattern having a displacement modulus equal to a fractional part of the mean fingerprint inter-ridge spacing and a displacement vector rotated through a vector argument in incremental steps;
- sampling means for sampling each of a plurality of independent sectors of the autocorrelation pattern, constituting collectively substantially the entire pattern, at each incremental step to obtain a set of data indicative of the intensity variations for each said sector for the incremental steps of the vector argument;
- and
- storing means for storing the sets of data.
A method of characterizing an image of a fingerprint under test to determine if the fingerprint under test matches a previously characterized fingerprint comprising the steps of:
- generating an image of the fingerprint under test by receiving a surface of a finger bearing the fingerprint under test and illuminating said surface;
- generating electrical signals representative of said image in response thereto;
- storing said electrical signals as a binary image of the fingerprint;
- producing a replica of the binary image;
- effectively overlying the replica on the binary image and generating an autocorrelation pattern having a displacement modulus equal to a fractional part of the mean fingerprint inter-ridge spacing and a displacement vector rotated through a vector argument in incremental steps;
- sampling each of a plurality of independent sectors of the autocorrelation pattern, constituting collectively substantially the entire pattern, at each incremental step to obtain a set of data indicative of the intensity variations for each said sector for the incremental steps of the vector argument;
- and
- storing the sets of data.
Dependencies are inferred from the claim text.