Patent ID: 7894642

Claim:
A method for checking fingerprints, comprising the steps of: recording, in succession, digital images of finger areas of a finger when passed over a sensor, wherein: said sensor is substantially smaller than a fingertip of said finger in a passing direction of said finger, said sensor extends in a direction perpendicular to said passing direction of said finger, and said recorded digital images correspond to small portions of said fingertip; and comparing, as each of the digital images is recorded in said succession, each of said recorded digital images with one or more reference images, wherein said one or more reference images represent at least one previously recorded reference fingerprint from a reference finger area that is considerably larger than the finger areas of each of the recorded digital images for the purpose of checking whether the finger that corresponds to the recorded digital images conforms to the reference fingerprint, and wherein said step of comparing each of said recorded digital images with the one or more reference images includes: generating a comparison image based on a latest one of the recorded digital images and said one or more reference images, said comparison image representing at least a part of the latest recorded digital image, determining a correspondence between the generated comparison image and a plurality of comparison areas in the reference image in a vicinity of a latest one of a plurality base areas, said plurality of base areas forming a chain of base areas below a common base area in the reference image, and selecting one of said comparison areas as a new base area in said reference image based on the determined correspondence between the generated comparison image and the selected comparison area.