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Fingerprint matching is the process of comparing sets of fingerprints associated with a crime with copies of fingerprints that are already on file with a law enforcement agency. In years past, the process of matching prints was a manual one that required careful scrutiny, and could be very time-consuming. Today, computer technology has made it possible to access vast databases of fingerprints and identify possible matches within a matter of minutes.
When it comes to fingerprint biometrics, there are two generally recognized classes or categories. One is known as the minutiae-based approach. With this strategy, the fingerprint matching is based on identifying characteristics of the prints that are less obvious than the more pronounced traits. In theory, this process makes it possible to narrow the range of possible matches, since it can eliminate consideration of prints that may share one or more major traits, but are devoid of some of the secondary aspects that are required in order to verify a match.
The second approach to fingerprint matching is known as the correlation-based method. This approach relies on not only the identifying characteristics of the print patterns, but also the positioning of those traits within the pattern. This involves the establishment of what are known as registration points along the body of the print, effectively providing a point of reference for the comparison process.
While both methods of fingerprint matching are effective, there are some drawbacks associated with each. In the case of the minutiae-based method, the quality of the prints must be quite high in order to verify a match. Prints that are somewhat blurred are much more difficult to deal with, since identifying and comparing secondary traits is less likely. At the same time, the effectiveness of the correlation-based approach depends on the ability of the examiner to establish a common registration point on the two sets of prints under comparison, and compensate for any differences in the rotation or image quality of the prints.
Since the advent of the computer in the middle of the 20th century, many law enforcement agencies have developed electronic fingerprint libraries that make it possible to quickly scan and identify possible matches. Most systems today make it easy to scan a new set of prints, then compare those prints with others found in the library. Using criteria built into the search function of the fingerprint software, the system will quickly identify and display any of the archived images that have a good chance of being a match. At that point, experts can perform visual comparisons and refine the results provided by the software.
In many countries around the world, national databases make it possible to conduct fingerprint matching using the resources created by law enforcement agencies throughout the country. Some countries also share their databases with other nations, making it possible to conduct fingerprint matching on an international scale. The end result of these efforts has been easier identification of matches within a shorter period of time, allowing law enforcement agencies to make arrests and thus solve crimes in less time.