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Iris recognition is a cutting-edge biometric identification method that uses high-definition cameras to capture the unique patterns of an individual’s iris. This technology is increasingly popular in modern smartphones, for secure authentication.

Iris recognition is a biometric technique that applies mathematical pattern-recognition algorithms to images of one or both irises. Each person’s iris pattern is complex, unique, and stable over time, making it ideal for identification—even between genetically identical individuals or between a person’s left and right eyes.

Understanding the Iris

The iris is a thin, circular structure in the eye that controls the size of the pupil and regulates the amount of light reaching the retina. The color of the iris determines eye color.

How Does Iris Scanning Work?

1. Image Acquisition

A digital or near-infrared (NIR) camera captures a high-resolution image of the iris.

2. Iris Localization

The system identifies and isolates the iris from the rest of the image by detecting:

• The center and edge of the pupil
• The edge of the iris
• Eyelids and eyelashes

Obstructions like eyelids, eyelashes, and reflections are excluded, leaving only the iris pixels.

3. Normalization (Daugman’s Rubber Sheet Model)

But images of Iris captured under different light intensity will not be the same. When eye is exposed to more light pupil will contract with the help of Iris and at low light pupil will be dilated.

This problem is addressed by a normalization method known as rubber sheet model.This model was developed by Daugman ,a professor at Harvard university. In simple words , this normalization procedure converts a circular shape (Iris) image into rectangular shape. Technically speaking a mathematical tansform is applied on the image to transform it from polar coordinates to Cartesian coordinates.

4. Pattern Matching

The extracted iris pattern is compared against previously stored templates for identification or authentication.

Advantages of Iris scanning and recognition

• Highly protected: It is an internal organ that is well protected against damage and wear by a highly transparent and sensitive membrane (the cornea). This distinguishes it from fingerprints, which can be difficult to recognize after years of certain types of manual labor.
• Unique Patterns:Even genetically identical individuals (and the left and right eyes of the same individual) have completely independent iris textures
• Non-invasive: An iris scan is like taking a photograph and can be performed from about 10 cm to a few meters away.
• Safe illumination: Illumination source is normal light or low energy infrared which is not harmful to human eyes. Retina scan is more invasive than iris scan.’’
• Works with Eyewear:Iris recognition works with clear contact lenses, eyeglasses, and non-mirrored sunglasses.

Disadvantages of iris scanners

• Susceptibility to Spoofing:Many commercial iris scanners can be easily fooled by a high quality image of an iris or face in place of the real thing.
• Lighting Sensitivity: The accuracy of scanners can be affected by changes in lighting.
• Cost: Iris scanners are significantly more expensive than some other forms of biometrics
• Medical Impact:Modern cataract surgery can cause change iris texture in such a way that iris pattern recognition is no longer feasible, or the probability of falsely rejected subjects is increased.

Iris scan vs Retina scan

Similarities
Iris and retinal scanning are known as “ocular-based” identification technologies, meaning they rely on unique physiological characteristics of the eye to identify an individual.
Differences
In retina scanner an infrared beam is projected into the eyes and reflected beam is used to construct the structure of retina. Unlike retina scanning, iris recognition uses camera technology with subtle infrared illumination to acquire images of the detail-rich, intricate structures of the iris. In retina scanning device need to be very close to the eyes. But ,since iris is visible outside the body camera need to place at a distance up to 10 inches.

Iris recognition stands out as a secure, reliable, and non-invasive biometric identification method. While it offers several advantages over other techniques, it’s important to consider its limitations and compare it with alternatives like retinal scanning for specific use cases.