NCJ Number
212923
Journal
Journal of Forensic Sciences Volume: 51 Issue: 1 Dated: January 2006 Pages: 100-102
Date Published
January 2006
Length
3 pages
Annotation
After describing a color deconvolution algorithm, this paper reports on its application to color-separation problems in document and fingerprint examinations.
Abstract
The authors first present the algorithm for color in a computer format. They then explain how free software available as a plug-in for Adobe Photoshop can be used to identify desired, undesired, and background colors by clicking on them, after which the algorithm is applied. This procedure can be useful in situations in which the colors and color differences in an image are important in an investigation. This paper presents three such cases. In one case it was suspected that changes and additions were made to original handwriting. In this case, subtle color differences in the ballpoint inks were detected between the initial handwriting and the subsequent changes. In the second case, handwritten entries were obliterated or masked with a similar but not identical ink. Color deconvolution improved the clarity of the original handwriting, except for a few parts where the covering ink layer was too thick to allow detection of the underlying ink color. In the third case, a fingerprint was visible on the inside of an envelope flap, but the background on which it was left impaired its visibility. Color deconvolution was successfully applied in two steps, first to remove the blue background print and then to remove the yellowish color of the envelope glue. The authors advise that color deconvolution is an excellent complementary technique when traditional optical techniques provide inconclusive results. Circumstances that limit the effectiveness of color deconvolution are outlined. 3 figures and 7 references