Patent ID: 7133541

Claim:
A method for analyzing electronically generated fingerprint images, which comprises the steps of: a) generating a plurality of fingerprint images subdivided into pixels in chronological succession, while a fingerprint is registered by a fingerprint sensor; b) determining, for each fingerprint image, a number of pixels containing a gray value exceeding a prescribed gray value; c) determining, for each subsequent fingerprint image, a difference between the number of pixels and the corresponding number of pixels of the previous fingerprint image; d) determining, for each of the differences, a ratio of the difference and one of the numbers of pixels of the previous fingerprint image and the subsequent fingerprint image; e) selecting the fingerprint images for which the ratio exceeds a prescribed limit value; f1) binarizing the selected fingerprint images by assigning a binary value one to the pixels containing the gray value exceeding the prescribed gray value and a binary value zero to remaining pixels; g1) superimposing the binarized fingerprint images by adding the binary values of the corresponding pixels to generate an image having gray value gradations; and h1) deciding by a distribution of the gray values whether the fingerprint is regarded as pertaining to a real live finger.