Method and device for selecting a fingerprint image in a sequence of images for authentication or identification

A device for selecting an image of a fingerprint for identifying or authenticating an individual, said selection device comprises an image capture module, said image being selected in a sequence of images acquired by said image capture module, the selection device comprising electronic circuitry configured to:

• a) acquire an image, referred to as the current image, comprising at least one fingerprint with said image capture module and segmenting said at least one fingerprint;
• b) determine a value representing a stability of said current image from said at least one segmented fingerprint;
• c) determine a value representing a sharpness of said current image from said at least one segmented fingerprint;
• d) determine a score for said current image, said score being a combination of said value representing a stability, of said value representing a sharpness and of a number of segmented fingerprints in said current image;
• e) select said current image for identifying or authenticating said individual in the case where said score is higher than a first threshold value, and otherwise store said current image in memory as the best image in the case where the score thereof is higher than a best score value, said best score value then being made equal to the score of said current image, and repeat steps a) to e), wherein determining a value representing a stability of said current image from said at least one segmented fingerprint comprises:
• for each segmented fingerprint, said fingerprint being segmented in the form of a region, referred to as the current region:
• determining a centre of gravity of said current region;
• determining a stability value of said current region according to a distance between the centre of gravity of said current region and the centre of gravity of at least one region determined in one of the f images preceding said current image timewise, f being an integer representing a number of images;
• determining a mean value of said determined stability values, said value representing a stability of said current image being equal to said mean value determined.