Fingerprint sensing system configured to determine if a finger contacts a fingerprint sensor

摘要

The invention relates to a method performed by a fingerprint sensing system of determining if a finger contacts a fingerprint sensor of the system, and a fingerprint sensing system performing method. In a first aspect of the invention, a method performed by a fingerprint sensing system is provided for determining if a finger contacts a fingerprint sensor of the fingerprint sensing system. The method comprises capturing an image of an object contacting the fingerprint sensor, determining an intensity for a plurality of pixels of the captured image, estimating local curvatures of pixel intensity variation in the captured image, and determining from the estimated local curvatures if local pixel intensity variation is dominated by a single direction, in which case the object on the sensor is considered to constitute a finger.