NCJ Number
204664
Journal
Journal of Forensic Identification Volume: 54 Issue: 2 Dated: March/April 2004 Pages: 150-155
Date Published
March 2004
Length
6 pages
Annotation
This article discusses another process for the elimination of background from fingerprint and other images by subtracting the background.
Abstract
This process involves substituting another item of the same type in exact register to obtain a substitute background image for purposes of the subtraction. A fingerprint was placed on a $20 Canadian bill. An image of the fingerprint was digitally captured. Another similar piece of currency in excellent condition was used to obtain a background pattern image. On a different day, the same general area of the pattern obstructing the fingerprint on the previous bill was captured. Using the registration function in ImagePro, the second image was brought into register with the first image. The registered background image was then subtracted from the first image. The background interference clearly evident in the first image was reduced significantly, as were the printed words that run into the fingerprint area. The fingerprint detail was consequently easier to examine. Four options exist for optimizing clarity of digital images through background subtraction. Only one (erasure) is invasive and requires the destruction of the evidence impression. Although the images in this study were processed in ImagePro Plus, filtration, erasure, and channel subtraction may also be completed successfully in Photoshop. The key with exhibit substitution is precision registration, an operation conducted easily in ImagePro. If registration of similar accuracy can be completed in other software options, the subsequent subtraction can be done equally successfully. 4 figures, 6 references