Browse Definitions:

Specific Biometric Techniques: Glossary

Acoustic Emission
Acoustic emission is a proprietary technique used in signature verification. As a user writes on a paper surface, the movement of the pen tip over the paper fibres generates acoustic emissions that are transmitted in the form of stress waves within the material of a writing block beneath the document being signed. The structure-borne elastic waves behave in materials in a similar way to sound waves in air and can be detected by a sensor attached to the writing block. 

AFIS (Automated Fingerprint Identification System)

AFIS is a highly specialized biometric system that compares a single finger image with a database of finger images. AFIS is predominantly used for law enforcement, but is also being put to use in civil applications. For law enforcement, finger images are collected from crime scenes, known as latents, or are taken from criminal suspects when they are arrested. In civilian applications, finger images may be captured by placing a finger on a scanner or by electronically scanning inked impressions on paper.

Auto-correlation is a proprietary fingerscanning technique. Two identical finger images are overlaid in the auto-correlation process, so that light and dark areas, known as Moiré fringes, are created.

A bifurcation is a branch made by more than one finger image ridge.

Binning is the process of classifying finger images according to finger image patterns. This predominantly takes place in law enforcement applications, a specialized technique used by some AFIS vendors. Finger images are categorized by characteristics like arches, loops and whorls and are held in smaller, separate databases (or bins) according to their category. Searches can be made against particular bins, thus speeding up the response time and accuracy of the AFIS search.

Body Odor
Body odor is physical biometric that analyses the unique chemical pattern made up by human body smell.

Booking is the process of capturing inked finger images on paper for subsequent processing by an AFIS.


Capacitance is a finger image capture technique that senses an electrical charge, from the contact of ridges, when a finger is placed on the surface of a sensor. 


DNA (Deoxyribonucleic acid) is a unique, measurable human characteristic, a combination of nucleic acids that constitute genetic code.

DPI (Dots Per Inch)
DPI is a measurement of resolution for finger image biometrics. 

DSV (Dynamic Signature Verification)
Synonym for 'Signature Verification.' 

Ear Shape

Ear shape is a lesser-known physical biometric that is characterized by the shape of the outer ear, lobes and bone structure.

Eigenface is a method of representing a human face as a linear deviation from a mean or average face.

An Eigenhead is a three dimensional version of Eigenface that also analyzes the shape of the head.

Face Monitoring

Face monitoring is a biometric application of face recognition technology where the biometric system monitors the attendance of an end user at a desktop.

Face Recognition
Face recognition is a physical biometric that analyses facial features.

Facial Thermogram
A facial thermogram is a specialized facial recognition technique that senses heat in the face caused by the flow of blood under the skin.


Filtering is the process of classifying finger images according to data which unrelated to the finger image itself. This may involve filtering by sex, age, hair color or other distinguishing factors.

Finger Geometry
Finger geometry refers to the physical biometric that analyses the shape and dimensions of one or more fingers.

Finger Image
A finger image is a physical biometric which looks at the patterns found in the tip of the finger.

The preferred terms are now 'Finger Image' and 'Fingerscanning.'

Fingerscanning is the process of finger image capture.

Fixed-Text System
The preferred term is 'Text-Dependent System.'

Free-Text System
The preferred term is 'Text-Independent System.'

Hand Geometry/Hand Recognition
Hand geometry is a physical biometric that involves analyzing and measuring the shape of the hand.

The IrisCode is the biometric data that is generated for each live iris presented. The code is a mathematical representation of the features of the iris. See also 'Biometric Data.'

Iris Features
Iris features refer to a number of features can be found in the iris. These are named corona, crypts, filaments, freckles, pits, radial furrows and striations.

Iris Recognition
Iris recognition is a physical biometric that analyses iris features, found in the colored ring of tissue that surrounds the pupil.

Keystroke Dynamics
Keystroke dynamics are a behavioral biometric under development that analyses typing rhythm when an end user types onto a keyboard.

A latent is an impression of a finger image collected from a crime scene.

Live Scan
The term live scan is typically used in conjunction with finger image technology. Synonym for 'Live Capture.' 


Minutiae are small details found in finger images such as ridge endings or bifurcations. 


Optical finger image capture is a technique that uses a light source, a prism and a platen to capture finger images. 


Palm refers to a physical biometric that analyses the palm of the hand. Typically this will involve an analysis of minutiae. 


The platen is the surface on which a finger is placed during optical finger image capture.


Retina refers to a physical biometric that analyses the layer of blood vessels situated at the back of the eye. 


Ridge refers to the raised marking found across the fingertip. See also 'Valley.' 

Ridge Ending

A ridge ending is the point at which a finger image ridge ends. 

Signature Verification

Signature verification is a behavioral biometric that analyses the way an end user signs his/ her name. The signing features such as speed, velocity and pressure exerted by a hand holding a pen are as important as the static shape of the finished signature. 


Speaker-dependent is a term sometimes used by speaker verification vendors to emphasize the fact their technology is designed to distinguish among voices. 

Speech Recognition

This is not a biometric and should not be confused with speaker verification. Speech recognition involves recognizing words as they are spoken and does not identify the speaker. 

Speaker Separation

Speaker separation is a technology that separates overlapping voices from each other and other background noises. 

Speaker verification

Speaker verification is a physical and behavioral biometric that analyses patterns in speech. 

SVAPI (Speaker Verification Application Program Interface)
SVAPI is a biometric API for speaker verification systems. 

Text-Dependent System

A text-dependent system requires a speaker to say a specific set of numbers or words.

Text-Independent System

A text-independent system that creates voiceprints from unconstrained speech and does not require a speaker to say a specific set of numbers or words.

Text-Prompted System
A speaker verification system that prompts the speaker to say randomly ordered numbers or words. The term 'Challenge-Response' is also used in a similar way to define text prompting. 


Thermal finger image capture is a technique that uses a sensor to sense heat from the finger and thus capture a finger image pattern. 

Ultrasound is a technique for finger image capture that uses acoustic waves to measure the density of a finger image pattern. 


Valleys are the corresponding marks found on either side of a finger image ridge. 

Veincheck/Vein Tree
A physical biometric under development that analyses the pattern of veins in the back of the hand. 

Voice Verification

The preferred term is 'Speaker Verification.'

Voice Print/Voiceprint

A representation of the acoustic information found in the voice of a speaker. 


Volatiles are produced by the chemical breakdown of body odor.

This was last updated in August 2011

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