Capturing Reliable Data for Computer-Based Forensic Handwriting Analysis II: Pen-position Activations

The forensic investigation of a questioned signature written on a piece of paper is a challenging task. Electronic pen-tablets for recording writing movements are considered valuable tools to assist in this effort. However, little is known about the precision and reliability of such electronic devices that are not intended as forensic equipment originally. Moreover, very few studies are conducted on the minimal requirements that would support appropriate forensic signature analysis. This paper presents a systematic study on the accuracy of online pen positions, which extends our previous work on the reliability of pen-force records. Implications of pen-tip displacements are discussed in the context of on- and offline signature data that is produced simultaneously. A basic method and advanced morphing algorithm are detailed that tackle (in)deterministic positioning errors. Experimental results on the processing of 100 authentic signatures and 93 skilled forgeries are reported finally.