Hyperspectral Imaging Advances Made
in the Characterization of Untreated Fingerprints
(A) Digital image of a latent fingerprint on white lined paper. (B) Unprocessed image of a latent fingerprint on white lined
paper at 470 nm. (C) Image of a processed latent fingerprint on white lined paper at 720 nm.
Graph portraying the increase of contrast between the fingerprint and background substrate in the raw versus the processed images.
Always looking to improve hyperspectral imaging (HSI) capabilities and applications, scientists at ChemImage recently concluded an HSI study that utilized improved data collection and image processing techniques to examine untreated latent fingerprints on challenging surfaces. More specifically, the research focused on aged and recently deposited latent fingerprints on white lined paper, white printer paper, a white business card, black magazine paper, Gorilla tape and aluminum foil.
As a nondestructive method of examination, HSI takes standard testing to the next level by adding a spectroscopic basis for sample analysis, enabling the enhancement of contrast between chemically different materials. In this particular experiment, hyperspectral images of the fingerprint’s ridge components and residues were collected from 400-720 nm using the ChemImage CONDOR
system and Xpert software. The hyperspectral datasets were then processed to increase the overall quality of the ridge details visible within the images.
In comparison to previously reported HSI studies, the result yielded a 42.8% overall improvement in contrast between the ridges and the substrate of the raw versus processed images without the use of chemical agents. This proves beneficial in situations where the preservation of the evidence or the fingerprint’s integrity is important.
“While the chemical development of fingerprints will always play an important role in forensic analyses, there are certain instances, such as prints deposited on valuable or old surfaces or those requiring DNA extraction, where it can be detrimental to use such methods,” said John Belechak
, Chief Operating Officer and Forensic Science Director at ChemImage. “We are encouraged by these findings because they bring our innovative hyperspectral imaging technology one step closer to being a validated alternative.”
Although results reported proved to be very promising, the study concluded that additional experimentation on evidence that’s crinkled, folded or curved and on fingerprints in various stages of aging would be advantageous.
Complete results from this research were published in the November/December 2010 issue of the Journal of Forensic Identification,
a scientific publication of the International Association of Identification, in an article titled “Improved Methods of Visible Hyperspectral Imaging Provide Enhanced Visualization of Untreated Latent Fingerprints.”
In addition to latent fingerprints, ChemImage is also researching the application of HSI for bloodstain visualization
and questioned document examination
(including security documents).
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