Technical Note Sequencing the intersections of printed strokes with writing instrument strokes using DocuCentre expert (PIA 6000-EDF) Ridamjeet Kaur a , Komal Saini a, ⁎, N.C. Sood b a Department of Forensic Science, Punjabi University, Patiala, Punjab, India b Directorate of Forensic Science, Ministry of Home Affairs, Govt. of. India, Shimla, Himachal Pradesh, India abstract article info Article history: Received 6 April 2012 Received in revised form 31 August 2012 Accepted 31 August 2012 Keywords: Questioned documents Intersecting strokes Laser printer Inkjet printer Dot-matrix printer Writing instruments Introduction of the digital techniques in document examination has encouraged the Forensic Document Ex- aminers to work with better accuracy in non-destructive ways. In this study, the examination of sequence of intersecting strokes of printers (inkjet printer, laser printer, dot-matrix printer) and typewriters with writing instruments (gel ink pen, ballpoint pen and fountain pen) of different colors was carried out by using Docucenter Expert via PIA-6000 software utilizing extended depth of focus. The continuity of the stroke is the only characteristic which has been observed at the point of intersection. © 2012 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved. 1. Introduction It is a great challenge for the Forensic Document Examiners (FDE's) to establish the sequence of intersecting strokes. Various techniques were applied and developed on the basis of different na- ture of intersecting inks by different authors [1–4]. Now-a-days, image enhancement systems are also employed for the examination of different types of sequence of crossing strokes [5]. Present endeavor has been made to determine the sequence of two intersecting strokes by using the Docucenter expert. In this, the sequence has been established by transforming the two dimensional profile of the captured image into three dimensional profiles via PIA-6000 software utilizing extended depth of focus. The surface under examination remains unaffected due to the non destructive na- ture of the technique and can be preserved for the future. The PIA-6000 software has a module that allows the repeated scanning of two dimensional images along with z-axis that stack them together giving a resultant focused image with a greater depth of field (DOF). The module sequentially transforms the apparently fo- cused two dimensional image into three dimensional reconstructed model image. It is assumed that the transformation of a 2D image into 3D reconstructed model image might provide some information at the point of intersection of two crossing strokes that can be used for the determination of their sequence in a better way. 2. Materials and methods Two brands of printers and typewriters with writing instruments were used to produce the heterogeneous intersecting lines (Table 1). The intersections include: • Laser printer strokes (black, blue, red and green colors) with ball- point pens', gel ink pens' and fountain pens' strokes of all colors (black, blue, red and green) and vice-versa; • Inkjet printer strokes (black, blue, red and green colors) with strokes of ballpoint pens, gel ink pens and fountain pens (black, blue, red and green) and vice-versa and • Dot-matrix printer and typewriter strokes of black color with ball- point pens, gel ink pens and fountain pen strokes of different colors (black, blue, red and green colors) and vice-versa. The exemplars (intersections) were prepared on white, smooth and non-coated paper (Power-Bilt multipurpose 215 × 345 mm, 5.6 g/m 2 ). Each type of intersection was prepared on three separate white sheets to get repetitive exemplars. The blind samples for the above said exemplars were also prepared. The key for these unknown exemplars was kept with one of the authors. The examination of all the intersecting strokes was carried out by using Docucenter expert. It has a digital camera of 5 mega pixels and an inbuild PIA-6000 software. The document was placed on the chamber platform of Docucenter expert and zoomed, so, only selected portion of document carrying intersecting strokes was displayed on the monitor. The fine focusing was adjusted by clicking ‘Auto Focus’ Science and Justice 53 (2013) 206–211 ⁎ Corresponding author. Tel.: +91 98149 90637. E-mail addresses: ridam_brar@yahoo.com (R. Kaur), komal2saini@yahoo.com (K. Saini). 1355-0306/$ – see front matter © 2012 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.scijus.2012.08.005 Contents lists available at SciVerse ScienceDirect Science and Justice journal homepage: www.elsevier.com/locate/scijus