Patent ID: 7330572

Claim:
A fingerprint authentication method comprising: a first step of collating features of input data based on a fingerprint input by a user with features of enrolled data; a second step of judging whether the input data are proper for authentication or not, said second step using a spatial frequency analysis of an input image represented by the input data; and a third step of authenticating the input data according to results of said first step and said second step; wherein said second step comprises: a fourth step of deciding a rectangular observation area on the input image; a fifth step of finding a Fourier transformed image from the input image; a sixth step of calculating feature values on the basis of plural frequency bands derived from the Fourier transformed image, said feature values representing features of the spatial frequency distribution of brightness of the input image; and a seventh step of deciding whether the input data are proper for the authentication or not on the basis of the feature values, wherein said sixth step is done by the use of variance of strength values corresponding to two predetermined spatial frequency bands in the Fourier transformed image.