How Fingerprint Scanners Work?
| Ms. Afrozbanu Mulla 09MCA16, FYMCA |
Biometrics consists of automated methods of recognizing a person based on unique physical characteristic. Each type of biometric system, while different in application, contains at least one similarity: the biometric must be based upon a distinguishable human attribute such as a person's fingerprint, iris, voice pattern or even facial pattern.
Today fingerprint devices are by far the most popular form of biometric security used, with a variety of systems on the market intended for general and mass market usage. Long gone are the huge bulky fingerprint scanners; now a fingerprint scanning device can be small enough to be incorporated into a laptop for security.
A fingerprint is made up of a pattern of ridges and furrows as well as characteristics that occur at Minutiae points (ridge bifurcation or a ridge ending). A fingerprint contains a number of unique physical characteristics called minutiae, which includes certain visible aspects of fingerprints such as ridges, ridge endings and bifurcations (forks in ridges). Minutiae are generally found in the core points of fingerprints, located near the centre of the fingertips.
There are a number of different ways to get an image of a fingerprint, and the most common methods today for electronic fingerprint readers are optical scanning and capacitance scanning. When a fingerprint is applied to - or passed over - the sensor window of the fingerprint reader, the fingerprint is scanned and a gray-scale image is captured. Special computer software then identifies the key minutiae points from the image. These points are then converted into a unique digital representation, called "template", comparable to a very big password.
When a fingerprint enrolment is done, only the fingerprint template is stored, not the actual image of the fingerprint. The fingerprint template is not only smaller than the finger image, but also faster to process when comparing two fingerprints.
Fingerprint recognition technology is divided into two distinct processes: verification and identification.
In the verification process the user states who he/she is and a fingerprint is taken and compared to the user's previously registered fingerprint. If the fingerprints match, the user is "verified" as who he/she says he/she is. Since the newly acquired fingerprint is compared to only one stored fingerprint, this is called a one-to-one matching process (1:1). As in the enrolment process, when fingerprint verification is done, only the fingerprint template is used in the comparison, not the actual image of the fingerprint.
In the identification process the user doesn't need to state who he/she is. A fingerprint is taken and compared to each fingerprint in the database of registered users. When a match occurs, the user is "identified" as the existing user the system found. Since the newly acquired fingerprint is compared to many stored fingerprints, this is called a one-to-many matching process (1:N). As in the verification process, when fingerprint identification is done, only the fingerprint template is used in the comparison, not the actual image of the fingerprint.
The actual fingerprint identification process will change slightly between products and systems. The basis of identification, however, is nearly the same. Standard systems are comprised of a sensor for scanning a fingerprint and a processor which stores the fingerprint database and software which compares and matches the fingerprint to the predefined database. Within the database, a fingerprint is usually matched to a reference number, or PIN number which is then matched to a person's name or account. In instances of security the match is generally used to allow or disallow access.
Fingerprint scanning essentially provides an identification of a person based on the acquisition and recognition of those unique patterns and ridges in a fingerprint. Although it may appear to be a simple process, fingerprint recognition involves the state-of-the-art technology in hardware, for the readers, and software, to process the fingerprint images and templates. But due to the effort of the hardware and software makers, all this complexity is hidden and fingerprint technology usage is nowadays as simple as touching the reader.
References:
1. http://www.biometrics.gov/Documents/FingerprintRec.pdf
2. http://en.wikipedia.org/wiki/Fingerprint_recognition
3. http://biometrics.cse.msu.edu/fingerprint.html
4. http://computer.howstuffworks.com/fingerprint-scanner.htm
5. http://www.economicexpert.com/a/Fingerprint.htm