Biometric fingerprinting is one method that is commonly used to automatically establish the identity of an individual. There are a few different techniques that a computer can use to compare fingerprints, and several methods that may be used to capture them for analysis. Most biometric fingerprinting is accomplished through either pattern recognition or the identification of minutia features. Capturing mechanisms include optical, ultrasonic, and capacitance, each of which uses a different method to create a digital picture of a fingerprint. Fingerprint recognition is a form of biometrics that is widely used in everything from secure facilities access to locking data on personal computers.
Fingerprint analysis was traditionally a skilled activity performed by highly trained professionals. Biometric fingerprinting is a similar process, though it uses a computer to examine a digitally captured image specifically to establish a person's identity. This is accomplished by imaging the fingerprint and comparing it to a stored picture. If the two match, identity is considered to have been established.
When comparing fingerprints, a computer program typically looks at both patterns and minutia features. The three main finger print patterns are arches, loops, and whorls. By determining which category a fingerprint falls into, a program may very quickly determine that two fingerprints do not match. If the two prints have the same type of pattern, then minutia features may be examined to provide a more accurate comparison. The three main features that are examined at this level are ridge endings, short ridges, and bifurcations.
In order to capture a fingerprint for digital analysis, any one of a variety of methods can be used. The optical method essentially uses a digital camera to take a picture of a fingerprint. This results in a picture that can then be analyzed. Optical biometric fingerprinting can have a few shortcomings, such as a difficulty in telling the difference between an actual finger and a picture. This can sometimes allow such a system to be bypassed by showing a picture of a fingerprint to the sensor.
Another method of biometric fingerprinting involves the use of piezoelectric transducers to generate an ultrasonic image. This method transmits ultrasonic sound waves through the outer skin layer, so it actually creates an image using the inner layer. The advantage conferred by this technology is that it can result in a good image even if the fingerprint is dirty or damaged.
Capacitive biometric fingerprinting works by using the inner dermal layer as one capacitor plate, the epidermis as a dielectric, and the sensor as the second plate. These sensors may use either passive or active capacitance. The principle that they operate by is that there is a difference in capacitance between ridge and valley portions of a fingerprint. Since the inner dermal layer is used, this method also allows accurate readings regardless of the condition of the epidermis.