Abstract:
Biometrics, which is formed from the two ancient Greek words bios and
metron which mean life and measure respectively, refers to two very different fields
of study and application. The first, which is the older and is used in biological
studies, is the collection, synthesis, analysis and management of biology. Biometrics in reference to biological
sciences, or biostatistics, has been studied since the early twentieth century.
More recently and incongruously, the term's meaning has been broadened
to include the study of methods for uniquely recognizing humans based upon one or
more intrinsic physical or behavioral traits.
Some researchers have coined the term behaviometrics for behavioral
biometrics such as typing rhythm or mouse gestures
where
the analysis can be done continuously
without interrupting or interfering with user activities.
Classification of some biometric traits
Biometric characteristics can be divided in two main classes, as represented
in figure on the right:
physiological are related to the shape of the body. The oldest traits,
that have been used for more than 100 years, are fingerprints. Other examples are
face recognition, hand geometry and iris recognition.
Recently, a new trend
has been developed
that merges human
perception to computer
database in a brain-machine interface. This approach has been referred to as cognitive
biometrics. Cognitive biometrics is based on specific responses of the brain to
stimuli which could be used to trigger a computer database search. Currently, cognitive
biometrics systems are being developed to use brain response to odor stimuli, facial
perception and mental performance for search
at ports and high security areas. These systems are based on use of functional
transcranial Doppler(fTCD) and functional transcranial Doppler spectroscopy(fTCDS)
to obtain brain responses, which are used to match a target odor, a target face
or target performance profile stored in a computer database. Thus, the precision
of human perception provides the data to match that stored in the computer with
improve sensitivity of the system.
behavioral are related to the behavior of a person. The first characteristic
to be used, still widely used today, is the signature. More modern approaches are
the study of keystroke dynamics and of voice.
Strictly speaking, voice is also a physiological trait because every
person has a different pitch, but voice recognition is mainly based on the study
of the way a person speaks, commonly classified as behavioral.
Other biometric strategies are being developed such as those based
on gait(way of walking), retina, hand veins, finger veins, ear canal, facial thermograph,
DNA, odor and scent and palm prints.
Iris Scanning
Iris scanning can seem very futuristic, but at the heart of the system
is a simple CCD digital camera. It uses both visible and near-infrared light to
take a clear, high-contrast picture of a person's iris. With near-infrared light,
a person's pupil is very black, making it easy for the computer to isolate the pupil and iris.
When you look into an iris scanner, either the camera focuses automatically
or you use a mirror or audible feedback from the system to make sure that you are
positioned correctly. Usually, your eye is 3 to 10 inches from the camera. When
the camera takes a picture, the computer locates:
The center of the pupil
The edge
of the pupil
The edge of the iris
The eyelids and eyelashes
It then analyzes the patterns in the iris and translates them into
a code.
Iris scanners are becoming more common in high-security applications
because people's eyes are so unique.
Some people confuse iris scans with retinal scans. Retinal scans, however, are an older technology that required a bright light to illuminate a person's retina. The sensor would then take a picture of the blood vessel structure in the back of the person's eye. Some people found retinal scans to be uncomfortable and invasive. People's retinas also change as they age, which could lead to inaccurate readings.
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