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NCJ Number: 148155 Find in a Library
Title: Computer Enhancement of Evidence Through Background Noise Suppression
Journal: Journal of Forensic Sciences  Volume:39  Issue:2  Dated:(March 1994)  Pages:537-546
Author(s): B E Dalyrymple; T Menzies
Date Published: 1994
Page Count: 10
Type: Report (Technical Assistance)
Format: Article
Language: English
Country: United States of America
Annotation: Computers have been used to enhance evidence for more than 20 years and can now be used with affordable software packages to enhance images in weak or obstructed evidence through the optimization of the signal to noise ratio.
Abstract: This signal optimization is achieved largely as a result of two factors. First, the digitization of the image gives the operator far greater control over each component of the image than is possible with a photographic (analog) image. Second, the computer has the ability to discriminate between 256 separate values of gray, from black (0) to white (255), in contrast to the approximately 32 separate values perceived by the human eye. The process does not add or create information that is not already present. In addition, the skill and experience of the analyst are directly related to the result. Specific techniques available through Imagepro software are fast Fourier transform, subtraction, predevelopment capture of background, signal filtration, signal erasure, and histogram equalization. Case examples, photographs, and 6 references (Author abstract modified)
Main Term(s): Science and Technology
Index Term(s): Computer aided investigations; Computer software; Forensic sciences; Photographic identification
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