Technical note: A novel 3D scan-based optical method for analyzing lines drawn at different pen pressure

Pen pressure is one of the important elements of handwriting and questioned document analysis which is also crucial to recognize forgery. In this paper, we present a new, non-contact, non-destructive, and relatively inexpensive technique to measure the width of the grooves made by the writing. Results demonstrate a clear difference in measured groove widths for varying pen pressure. The effect of passing a written or signed paper in different types of printers has also been studied. A clear decrease of the groove depth was noted when passing the document through a laser printer. An ink jet printer only resulted in a small decrease of the groove depth, while no effect could be detected from a dot matrix printer.