Robust and applicable handwriting biometrics

Dissertation by Axel A. Brink, University of Groningen, November 2011. ISBN: 978-90-367-5139-1 (printed) / 978-90-367-5174-2 (electronic). Defended on December 2, 2011, in Groningen, the Netherlands.


Robust and applicable handwriting biometrics
by Axel A. Brink
(PDF, 14 MB)


Handwriting biometrics is the attribution of writers to handwriting based on characteristics in handwriting that are measured by the computer. There are two variants: one-to-one comparison (verification) and identification: searching for similar handwriting in a collection.

In the first part of the dissertation the robustness of handwriting biometrics is investigated. First, it was shown that good performance is possible if at least one hundred characters have been written. Second, it was found that crossed-out text is no impediment. Third, it was found that the simplest type of handwriting duisguise, a change of slant, can be largely corrected by shearing, but not completely. Apparently, more changes are applied to the handwriting apart from a shear effect.

In the second part, methods are discussed to increase robustness and applicability of handwriting biometrics. A new technique is presented for measuring handwriting characteristics, inspired by modern paleography. It comes down to automatically measuring the width and direction of the ink trace at thousands of points. This is a good combination: the technique performs very well, on modern handwriting as well as on medieval handwriting. Second, it is suggested to make handwriting biometrics more explainable, which is important in court, by expressing it as a relative position with respect to a few typical handwritings.

In addition, an easy-to-use computer program was developed: GIWIS. It is being used by historians and linguists to group historical handwriting, for the benefit of historical research. It can also be used to identify suspects in a crime in which handwriting is involved.

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Last modified: 2012-02-03