Use of Exterior Contours and Shape Features in Off-line Signature Verification

  • Authors:
  • Siyuan Chen;Sargur Srihari

  • Affiliations:
  • University at Buffalo, State University of New York, Buffalo, USA;University at Buffalo, State University of New York, Buffalo, USA

  • Venue:
  • ICDAR '05 Proceedings of the Eighth International Conference on Document Analysis and Recognition
  • Year:
  • 2005

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Abstract

An approach to off-line signature verification, one with an on-line flavor, is described. A sequence of data is obtained by tracing the exterior contour of the signature which allows the application of string-matching algorithms. The upper and lower contours of the signature are first determined by ignoring small gaps between signature components. The contours are combined into a single sequence so as to define a pseudo-writing path. To match two signatures a non-linear normalization method, viz., dynamic time warping, is applied to segment them into curves. Shape descriptors based on Zernike moments are extracted as features from each segment. A harmonic distance is used for measuring signature similarity. Performance is significantly better than that of a word-shape based signature verification method. When the two methods are combined, the overall performance is significantly better than either method alone. With a database of 1320 genuines and 1320 forgeries the combination method has an accuracy of 95% (with 20% rejection) which is comparable to that of on-line systems.