A review of calibration methods for biometric systems in forensic applications

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    Abstract

    When, in a criminal case there are traces from a crime scene - e.g., finger marks or facial recordings from a surveillance camera - as well as a suspect, the judge has to accept either the hypothesis \emph{$H_{p}$} of the prosecution, stating that the trace originates from the subject, or the hypothesis of the defense \emph{$H_d$}, stating the opposite. The current practice is that forensic experts provide a degree of support for either of the two hypotheses, based on their examinations of the trace and reference data - e.g., fingerprints or photos - taken from the suspect. There is a growing interest in a more objective quantitative support for these hypotheses based on the output of biometric systems instead of manual comparison. However, the output of a score-based biometric system is not directly suitable for quantifying the evidential value contained in a trace. A suitable measure that is gradually becoming accepted in the forensic community is the Likelihood Ratio (LR) which is the ratio of the probability of evidence given \emph{$H_p$} and the probability of evidence given \emph{$H_d$}. In this paper we study and compare different score-to-LR conversion methods (called calibration methods). We include four methods in this comparative study: Kernel Density Estimation (KDE), Logistic Regression (Log Reg), Histogram Binning (HB), and Pool Adjacent Violators (PAV). Useful statistics such as mean and bias of the bootstrap distribution of \emph{LRs} for a single score value are calculated for each method varying population sizes and score location.
    Original languageEnglish
    Title of host publication33rd Symposium on Information Theory in the Benelux and the 2nd Joint WIC/IEEE Symposium on Information Theory and Signal Processing in the Benelux 2012
    Place of PublicationEnschede
    PublisherWerkgemeenschap voor Informatie- en Communicatietheorie (WIC)
    Pages126-133
    Number of pages8
    ISBN (Print)978-90-365-3383-6
    Publication statusPublished - May 2012
    Event33rd WIC Symposium on Information Theory in the Benelux and the 2nd Joint WIC/IEEE Symposium on Information Theory and Signal Processing in the Benelux 2012 - Boekelo, Netherlands
    Duration: 24 May 201225 May 2012
    Conference number: 33

    Conference

    Conference33rd WIC Symposium on Information Theory in the Benelux and the 2nd Joint WIC/IEEE Symposium on Information Theory and Signal Processing in the Benelux 2012
    CountryNetherlands
    CityBoekelo
    Period24/05/1225/05/12

    Keywords

    • METIS-287889
    • EWI-21962
    • SCS-Safety
    • IR-80693

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  • Cite this

    Ali, T., Spreeuwers, L., & Veldhuis, R. (2012). A review of calibration methods for biometric systems in forensic applications. In 33rd Symposium on Information Theory in the Benelux and the 2nd Joint WIC/IEEE Symposium on Information Theory and Signal Processing in the Benelux 2012 (pp. 126-133). Enschede: Werkgemeenschap voor Informatie- en Communicatietheorie (WIC).