Siemens Aktiengesellschaft

Infineon Technologies Ag

Brigitte Wirtz

Hanno Melzner

Stefan Jung

Ernst Haselsteiner

Christoph Maggioni

Henning Lorch

Peter Morguet

Chistoph Maggioni

Angela Engels

In a method for forgery recognition in the fingerprint recognition, at first an image sequence is captured, which comprises a plurality of images of the fingerprint to be recognized. From at least two images capturing a texture captures a differential image. The texture will be compared with a predetermined texture in order to determine whether the captured image sequence comes from a real finger or from an imitation.

Method for forgery recognition in fingerprint recognition by using a texture classification of gray scale differential images

A method for analyzing fingerprint images includes picking up a sequence of images at very short time intervals, while a finger is being placed onto an electronic fingerprint sensor. A criterion for recognizing a live finger is extracted from variations in the images. The images are defined as a pixel raster having different gray values, with the aid of which the pixels are assigned binary values of zero or one. Significant changes in the values are detected and compared, with the aid of distinctive numbers or the like, to known typical changes that occur regularly in a particular image class.

Method for analyzing fingerprint images

In a fingerprint sensor that effects capacitive measurement, a sequence of fingerprint images is recorded while a finger is placed on to the sensor. By comparing the best image with previous images of the sequence, the real constituent parts of the present image are determined and the remaining constituent parts are eliminated from the best image. Thus, residual prints and disturbance components brought about by contamination of the bearing area can be eliminated from the fingerprint image.

Method for disturbance-component-free image acquisition by an electronic sensor

What the method assures is that natural changes in the signature of a person are not reflected in the form of increasing rejections within the framework of an authentification of this person on the basis of the person's signature. &ldquo;Natural&rdquo; variation in the signature of the person is adapted to a reference signature, whereby an appropriate &ldquo;distance&rdquo; from a possible forged signature is adhered to so that adaptation is not undertaken in the direction of a potential forger. To that end, the signature is evaluated dependent on its distance from the reference signature and this evaluation criterion is divided into ranges that reflect the quality of the signature. Proceeding from the quality, an evaluation is possible as to whether or not an adaptation is implemented.

Method for computer-adaptation of a reference data set on the basis of at least one input data set

In a method for determining a reference autograph character string on the basis of a set of sample autograph character strings from the same writer, a particularly characteristic autograph character string can be selected from a set of produced sample autograph character strings, e.g. signatures. In signature verification, such references are needed to serve as a comparison measure in the identification of the signer. The method according to the invention divides the produced character strings of a sample set of signatures into strokes according to the execution, and compares individual strokes with respect to the recorded dynamic parameters, such as for example pressure and locus coordinates and writing speed, in order to enable the determination of the deviation of all the strokes of the sample character strings from one another. From the set of sample character strings, that string is then selected as the reference character string which comprises the smallest values to the totality of all other sample character strings. In this way it is ensured that the most representative sample character string is brought into use as the reference character string.

Method for determining a reference autograph character string on the

Method for detecting the spatial position and rotational position of

In a method for dynamic verification of an autograph character string on the basis of a reference autograph character string, the principle of dynamic programming is used for signature verification. Digitized handwriting data as functions of time are first normalized by a standard method. The verification works according to the invention with structural units of the signature, so-called strokes, which result from the writing motions with a raised or, respectively, lowered stylus. The particular concept is to base the dynamic programming on a cost function that combines several handwriting data. The stable structural portions of the signature are more strongly weighted in the method than unstable ones. This leads to a higher verification performance than in standard methods. The method also enables the comparison of signals having different numbers of strokes, so that omissions or additional strokes can be correctly evaluated, by predetermining syntactic rules for their treatment.

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Holzkirchen, Germany

Brigitte Wirtz