Impact of time variability in off-line writer identification and verification

Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. F. Alonso-Fernández, J. Fiérrez, A. Gilpérez, J Ortega-García, "Impact of time variability in off-line writer identification and verification" in 6th International Symposium on Image and Signal Processing and Analysis (ISPA), Salzburg (Austria), 2009, pp. 540 - 545One of the biggest challenges in person recognition using biometric systems is the variability in the acquired data. In this paper, we evaluate the effects of an increasing time lapse between reference and test biometric data consisting of static images of handwritten signatures and texts. We use for our experiments two recognition approaches exploiting information at the global and local levels, and the BiosecurlD database, containing 3,724 signature images and 532 texts of 133 individuals acquired in four acquisition sessions distributed along a 4 months time span. We report results of the recognition systems working both in verification (one-to-one) and identification (one-to-many) mode. The results show the extent of the impact that the time separation between samples under comparison has on the recognition rates, being the local approach more robust to the time lapse than the global one. We also observe in our experiments that recognition based on handwritten texts provides higher accuracy than recognition based on signatures.This work has been supported by Spanish MCYT TEC2006-13141-C03-03 project

Off-line signature verification using contour features

Proceedings of the International Conference on Frontiers in Hadwriting Recognition (ICFHR 2008)An off-line signature verification system based on contour features is presented. It works at the local image level, and encodes directional properties of signature contours and the length of regions enclosed inside letters. Results obtained on a sub-corpus of the MCYT signature database shows that directional-based features work much better than length-based features. Results are comparable to existing approaches based on different features. It is also observed that combination of the proposed features does not provide improvements in performance, maybe to some existing correlation among them.This work has been supported by Spanish project TEC2006-13141-C03-03, and by European Commission IST-2002-507634 Biosecure NoE

Robustness of signature verification systems to imitators with increasing skills

Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. F. Alonso-Fernández, J. Fiérrez, A. Gilpérez, J. Galbally, J. Ortega-García, "Robustness of Signature Verification Systems to Imitators with Increasing Skills" in International Conference on Document Analysis and Recognition (ICDAR), Barcelona (Madrid), 2009, 728 - 732In this paper, we study the impact of an incremental level of skill in the forgeries against signature verification systems. Experiments are carried out using both off-line systems, involving the discrimination of signatures written on a piece of paper, and on-line systems, in which dynamic information of the signing process (such as velocity and acceleration) is also available. We use for our experiments the BiosecurID database, which contains both on-line and off-line versions of signatures, acquired in four sessions across a 4 month time span with incremental level of skill in the forgeries for different sessions. We compare several scenarios with different size and variability of the enrolment set, showing that the problem of skilled forgeries can be alleviated as we consider more signatures for enrolment.This work has been supported by the TEC2006-13141- C03-03 project of the Spanish Ministry of Science and Technology