How does Iris scanning work?

Biometrics or the use of unique physical characteristics of individuals is soon becoming a widely used method for identification. Various forms of biometrics are used like fingerprint recognition, iris recognition and facial recognition. Among these iris recognition has proven to be the most reliable form of identification. The fact that the unique pattern of iris remains unchanged during a person’s lifetime makes it more reliable than the other forms of recognition.

Before studying how iris scanning works, let us first understand the basic structure of a human eye. Iris is the coloured part of our eye. It is the pigment melanin which gives iris its colour. The more the pigment, the browner the iris is. The absence of melanin results in the colour blue. The iris has a dark coloured pupil at its centre. Iris is surrounded by the white sclera. The eye is covered by a transparent layer known as cornea. Iris is responsible for controlling the size and diameter of the pupil
and thus the amount of light which reaches the retina.

The development of iris starts in the gestation period itself. Each eye of an individual has a different iris pattern. Even, identical twins have different patterns. Iris is well protected by the cornea and hence it is least susceptible to damage by the environment. As compared to fingerprint recognition which requires direct contact with the scanner, iris scanning can be done from a distance. These advantages make identification of individuals using iris scanning more reliable. Iris recognition works with eye glasses, contact lenses and sunglasses too.

Iris recognition involves scanning of the iris and comparing it with already existing images in the database. When the identity of an individual needs to be verified, the image of the eye is captured by means of a digital camera using both visible light and near infrared light(NIR). NIR has a slightly larger wavelength than visible light and is able to capture the distinctive features of even dark coloured eyes which visible light is not able to capture. The digital image thus scanned is converted into a 512 byte IrisCode and compared with the codes stored in the database. If a match is found in the database, the identity of the person is  validated.




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