Explainable offline automatic signature verifier to support forensic handwriting examiners

TL;DR

This paper introduces an explainable offline automatic signature verification system that uses a universal background model to support forensic handwriting examiners, balancing interpretability with competitive accuracy.

Contribution

A novel explainable signature verification method based on a universal background model, enabling understandable decisions for forensic applications.

Findings

Achieves competitive performance with state-of-the-art systems

Supports explainability for forensic handwriting examiners

Effective in challenging 1 vs 1 signature comparisons

Abstract

Signature verification is a critical task in many applications, including forensic science, legal judgments, and financial markets. However, current signature verification systems are often difficult to explain, which can limit their acceptance in these applications. In this paper, we propose a novel explainable offline automatic signature verifier (ASV) to support forensic handwriting examiners. Our ASV is based on a universal background model (UBM) constructed from offline signature images. It allows us to assign a questioned signature to the UBM and to a reference set of known signatures using simple distance measures. This makes it possible to explain the verifier's decision in a way that is understandable to non experts. We evaluated our ASV on publicly available databases and found that it achieves competitive performance with state of the art ASVs, even when challenging 1 versus 1 comparison are considered. Our results demonstrate that it is possible to develop an explainable ASV that is also competitive in terms of performance. We believe that our ASV has the potential to improve the acceptance of signature verification in critical applications such as forensic science and legal judgments.