Techniques for Digtal Enhancement of Latent Prints Obscured by Disruptive Backgrounds

• NCJ Number: 204663
• Journal: Journal of Forensic Identification Volume: 54 Issue: 2 Dated: March/April 2004 Pages: 141-149
• Author(s): Steve Scarborough; Alex Dziemieszko
• Date Published: March 2004
• Length: 9 pages
• Publication Format: Article
• Publication Type: Report (Study/Research)
• Language: English
• Country: United States of America

Annotation

This article discusses a study to develop a consistent technique for removing background and foreground distractions in order to enhance latent prints.

Abstract

A number of techniques were identified and refined that are effective for these types of problem cases. The techniques use a combination of imaging functions and can be easily followed. They are useful for the digital enhancement of inked prints on forged checks that are obscured by the stamps or printing on the check. They are especially useful when the colors of the inks, the colors of the background, and the latent print are of similar shades. Experimentation is necessary in order to find the technique that is most appropriate for the type of distracting background present in the evidence image. Although one technique works for distracting overlay colors, another technique might work better for distracting colored patterns. The techniques discussed here were generalized in an attempt to apply to the most common situations of background removal. These are the techniques that have been most successful on the types of evidence described, but may not be applicable for some other types of evidence. In cases where the color (not the pattern) is the distracter, these techniques can give better results than those achieved with Fast Fourier Transform (FFT) filters. Multiple techniques may be necessary when there are a number of background distracters. It was found that there are multiple methods of removing disruptive backgrounds and there is no universal technique that works for every type of background. The enhancement technique varies, depending upon the type of print and the type of background. When properly applied, the results of using these techniques can be quite dramatic, especially when a partially obscured print is rendered entirely visible by subtracting all of the background images and colors. 3 figures