NCJ Number
136869
Journal
Journal of Forensic Sciences Volume: 37 Issue: 3 Dated: (May 1992) Pages: 797-807
Date Published
1992
Length
11 pages
Annotation
Two experimental applications of digital image processing to the examination of questioned documents are evaluated.
Abstract
The first application involves a comparison of digital image processing, electrostatic detection apparatus (ESDA) processing, side lighting, and photography in the decipherment of indented writing. The best results are demonstrated by first using the ESDA and then digitally enhancing the ESDA lift with a high-pass sharpening filter. The second application is the use of image processing equipment to make fracture match comparisons to associate carbon film typewriter ribbons with questioned typescript. Split screen images and image overlays are shown to be very effective techniques for this kind of examination. A benefit of the fracture match identification system is that large numbers of documents and letters can be examined simply by removing one and placing another under the camera. In addition, the system is less stressful on the eyes than the comparison microscope. If a printer is part of the image enhancement hardware, a printed picture can be made of the match for case file notes and courtroom demonstration. The image can also be saved on a disk for future use. 2 references and 8 figures (Author abstract modified)