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This article is part of the series Recent Advances in Biometric Systems: A Signal Processing Perspective.

Open Access Research Article

Online Signature Verification Using Fourier Descriptors

Berrin Yanikoglu1* and Alisher Kholmatov2

Author Affiliations

1 Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul 34956, Turkey

2 National Research Institute of Electronics and Cryptology (UEKAE), Scientific and Technological Research Council of Turkey (TUBITAK), Gebze, Kocaeli 41470, Turkey

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EURASIP Journal on Advances in Signal Processing 2009, 2009:260516  doi:10.1155/2009/260516

The electronic version of this article is the complete one and can be found online at: http://asp.eurasipjournals.com/content/2009/1/260516

Received:27 October 2008
Revisions received:25 March 2009
Accepted:25 July 2009
Published:16 September 2009

© 2009 The Author(s).

This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We present a novel online signature verification system based on the Fast Fourier Transform. The advantage of using the Fourier domain is the ability to compactly represent an online signature using a fixed number of coefficients. The fixed-length representation leads to fast matching algorithms and is essential in certain applications. The challenge on the other hand is to find the right preprocessing steps and matching algorithm for this representation. We report on the effectiveness of the proposed method, along with the effects of individual preprocessing and normalization steps, based on comprehensive tests over two public signature databases. We also propose to use the pen-up duration information in identifying forgeries. The best results obtained on the SUSIG-Visual subcorpus and the MCYT-100 database are 6.2% and 12.1% error rate on skilled forgeries, respectively. The fusion of the proposed system with our state-of-the-art Dynamic Time Warping (DTW) system lowers the error rate of the DTW system by up to about 25%. While the current error rates are higher than state-of-the-art results for these databases, as an approach using global features, the system possesses many advantages. Considering also the suggested improvements, the FFT system shows promise both as a stand-alone system and especially in combination with approaches that are based on local features.

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