Apparatus and computer-implemented method for fingerprint based authentication

A computer-implemented method of configuring a first classifier by supervised training to distinguish live fingerprint images from imitated fingerprint images;

• comprising the steps of:
• a) acquiring multiple sets of fingerprint images, and generating pairs of images thereof that matches;
• wherein for each pair of fingerprint images, first feature vectors are computed from a first fingerprint image and second feature vectors are computed from a second fingerprint image;
• b) for each pair of fingerprint images, computing a plurality of values of the similarity measure that measures the similarity between the images in the pair of fingerprint images;
• wherein step a) is performed on fingerprint images acquired from live fingers, and wherein, in step b), the plurality of values of the similarity measure are collectively labelled by a first label;
• and
• wherein step a) is performed on fingerprint images acquired from imitated fingers, and wherein, in step b), the plurality of values of the similarity measure are collectively labelled by a second label;
• and
• wherein the first classifier is trained from one or both of a first training set comprising the plurality of values of the similarity measure obtained from live fingers with the first label as a supervisory signal and a second training set comprising the plurality of values of the similarity measure obtained from imitated fingers with the second label as a supervisory signal;
• c) storing a computer-readable representation of the classifier.

An apparatus with a processing unit coupled to a fingerprint sensor, comprising:

• a fingerprint acquisition unit configured to acquire a present fingerprint image from a fingerprint sensor;
• a storage configured to store a plurality of second feature vectors of an enrolled fingerprint image;
• a processing unit configured to:
• compute a plurality of first feature vectors of the present fingerprint image;
• apply a similarity measure to compute a plurality of similarity values that represents a degree of similarity between a set of first feature vectors and second feature vectors;
• perform first classification of at least a portion of the plurality of similarity values to generate a first signal indicative of whether the present fingerprint image falls within a class defined from enrolled images;
• perform second classification of at least a portion of the plurality of similarity values to generate a second signal indicative of whether the present fingerprint image falls within a class of fingerprints from live fingers or a class of fingerprints from imitated fingers;
• and
• generate an authentication signal from the first signal and the second signal;
• matching first feature vectors and second feature vectors to form a first set of matching pairs;
• reducing the first set of matching pairs to a second set of matching pairs that comprises those matching pairs that agree to a uniform geometrical transformation;
• wherein computation of the plurality of values of the similarity measure is restrained to be computed from the pairs of first feature vectors and second feature vectors that falls into the second set of matching pairs;
• wherein the first feature vectors and the second feature vectors that fall outside one or both of the first set of matching pairs and the second set of matching pairs are collected in a first set of outlier features;
• and
• wherein one or both of the first classification and the second classification includes all or at least a portion of the outlier features in generating the first signal and the second signal, respectively.