Towards robust writer verification by correcting unnatural slant

  • Authors:

  • A. A. Brink;R. M. J. Niels;R. A. van Batenburg;C. E. van den Heuvel;L. R. B. Schomaker

  • Affiliations:

  • Institute of Artificial Intelligence and Cognitive Engineering (ALICE), University of Groningen, P.O. Box 407, 9700 AK Groningen, The Netherlands;Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, P.O. Box 9104, 6500 HE Nijmegen, The Netherlands;Institute of Artificial Intelligence and Cognitive Engineering (ALICE), University of Groningen, P.O. Box 407, 9700 AK Groningen, The Netherlands;Netherlands Forensic Institute, P.O. Box 24044, 2490 AA Den Haag, The Netherlands;Institute of Artificial Intelligence and Cognitive Engineering (ALICE), University of Groningen, P.O. Box 407, 9700 AK Groningen, The Netherlands

  • Venue:
  • Pattern Recognition Letters
  • Year:
  • 2011

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Abstract

Slant is a salient feature of Western handwriting and it is considered to be an important writer-specific feature. In disguised handwriting however, slant is often modified. It was tested whether slant is indeed an important factor and it was tested whether the distorting effect of deliberate slant change can be countered by a simple shear transform. This was done in two off-line writer verification experiments in image processing conditions of slant elimination and slant correction. The experiments were performed using three features based on statistical pattern recognition, including the state-of-the-art features Fraglets and Hinge. A new public dataset was created and used, containing natural and slanted handwriting by 47 writers. A striking result is that the average natural slant value is much less important for biometric systems than is usually assumed: eliminating slant yields just a 1-5% performance loss. A second result is that the effects of deliberate slant change cannot be fully countered by a simple shear transform: it raises performance on the distorted handwriting from 53-68% to 64-90%, but this is still lower than normal operation on natural handwriting: 97-100%.