A fingerprint is an impression left by the friction ridges of a human finger. The recovery of partial fingerprints from a crime scene is an important method of forensic science. Moisture and grease on a finger result in fingerprints on surfaces such as glass or metal. Deliberate impressions of entire fingerprints can be obtained by ink or other substances transferred from the peaks of friction ridges on the skin to a smooth surface such as paper. Fingerprint records normally contain impressions from the pad on the last joint of fingers and thumbs, though fingerprint cards also typically record portions of lower joint areas of the fingers.
Human fingerprints are detailed, nearly unique, difficult to alter, and durable over the life of an individual, making them suitable as long-term markers of human identity. They may be employed by police or other authorities to identify individuals who wish to conceal their identity, or to identify people who are incapacitated or deceased and thus unable to identify themselves, as in the aftermath of a natural.
A fingerprint is formed on any opaque surface and is the impression of the friction ridges on the finger of a human. The matching of two fingerprints is among the most widely used and most reliable biometric techniques. Fingerprint matching considers only the obvious features of a fingerprint.
A friction ridge is a raised portion of the epidermis on the digits (fingers and toes), the palm of the hand or the sole of the foot, consisting of one or more connected ridge units of friction ridge skin citation needed] These are sometimes known as “epidermal ridges” which are caused by the underlying interface between the dermal papillae of the dermis and the interpapillary (rete) pegs of the epidermis. These epidermal ridges serve to amplify vibrations triggered, for example, when fingertips brush across an uneven surface, better transmitting the signals to sensory nerves involved in fine texture perception. These ridges may also assist in gripping rough surfaces and may improve surface contact in wet conditions.
The unique nature of a fingerprint makes it ideal for use in automated recognition systems. A fingerprint is made of a series of ridges and grooves. Once a fingerprint is captured the system locates the minutia points. These minutia points occur where the lines of the ridges begin, end, branch off and merge with other ridge lines. These points are then mapped and a line is drawn between each point. This creates a map of how each point relates to the other points. The map is then stored as a data stream called a minutia template in a database for future comparison with other presented fingerprints. It is important to note that during the entire process no fingerprint images are stored on the system and a fingerprint image cannot be recreated from the minutia template.
Differences between Identification & Authentication
Identification (also known as 1:Many, 1:X or One to Many)
Using specialised indexing techniques a sample is effectively matched against all templates in the database. In specialised high end systems a sample can be matched in against hundreds of thousands
Put simply, a person does not have to provide any input other than their biometric.
Authentication (also known as Verification, 1:1 or One to One)
The sample is matched against one pre-selected template.
Put simply, a person swipes a card or enters a user code to select a biometric template to match against.
Measuring biometric effectiveness
There are 2 commonly used gauges for measuring the effectiveness of biometrics matching technology.
1. False Rejection Rate (FRR) as known as False Non-Match Rate (FNMR)
FRR is a value that measures the percentage of times a biometric sample is matched against a single or multiple biometric templates where a biometric template exists but the likeness between the sample and template is below the decision threshold setting so no match occurs.
Put simply, it’s the number of times people do not get identified when they should be identified.
2. False Accept Rate (FAR) also know as False Match Rate (FMR)
FAR is a value that measures the percentage of times a biometric sample is matched against a single or multiple biometric templates where a biometric template does not exist but the likeness between the sample and template is above the decision threshold setting so a match incorrectly occurs.
Put simply, it’s the number of times people get identified when they should not be identified.