Signature verification data compression for storage on an identification

Abstract

Apparatus and methods are described which take advantage of the peculiar characteristics of dynamic signature data while segmenting and compressing such data for storage on a limited capacity device. Compression is accomplished by digital oversampling, segmenting, filtering, decimating and later interpolating reference signature data, thereby allowing storage in compressed form without significant matching degradation. The pen down and pen up information which define signature segments is separated from the pressure waveform and stored in a separate array for each reference signature. The acceleration and pressure data are then filtered, decimated and stored for each reference signature. Later, during identity verification, the stored acceleration and pressure data are restored to an oversampled rate by interpolation. To verify the identity of a person supplying a trial signature, each segment of the trial signature is compared with corresponding segments of one or more of the stored reference signatures.