Sequencing of Intersecting Strokes of Printed Ink Lines with Writing Pen Inks Using Image Processing Software

Abstract

Determining the sequence of intersecting strokes is a longstanding challenge in questioned document examination, particularly
with the widespread use of computer printers and writing instruments in modern documents. This study aimed to establish the
sequence of intersecting strokes between laser printer toner, inkjet printer inks, and ballpoint and gel pen inks using Adobe
Photoshop CC 2021. A total of 2,880 intersecting stroke samples were prepared using laser and inkjet printers with ballpoint
and gel pens on different paper substrates. The samples were analysed through image processing based on characteristics
such as toner compression, toner expansion, and luminous appearance at the point of intersection. The proposed method
successfully determined the sequence in 2,304 (80%) of the samples. Homogeneous combinations of red and blue inkjet printer
inks with corresponding pen inks produced inconclusive results. The findings demonstrate that Adobe Photoshop provides a
simple, objective, cost-effective, and non-destructive approach for sequence determination, offering a practical alternative for
routine forensic document examination.