In this blog post, we’ll explore why iris recognition is used as a biometric technology, the characteristics of the iris, the principles behind the recognition process, and the latest iris recognition technologies being applied across various fields.
Advances in Information Security and Biometric Technology
In today’s digital society, information security is a critical factor. Even the smartphones used by people today employ various methods to protect information. The use of multiple authentication technologies—ranging from passwords combining numbers and letters to pattern locks, fingerprint recognition, facial recognition, and iris recognition—has significantly improved the security and convenience of smartphones.
Biometric technology is widely used not only for unlocking smartphones but also for identity verification in mobile financial services, electronic signatures, and various online services. In the past, digital certificates were the primary means of authentication, but today, joint certificates and private simplified authentication services are used in conjunction, and biometric authentication is making these processes even faster and more convenient.
This security method, which uses a part of the body as a password, is utilized not only in smartphones but also in various fields requiring high security, such as automated immigration screening at airports, financial institutions, research facilities, and access control for critical national infrastructure.
What is biometric technology?
Biometrics refers to technology that verifies a person’s identity using their physical or behavioral characteristics. Since it relies on unique traits that differ from person to person, it offers the advantage of eliminating the need to carry separate cards or keys and the need to remember passwords. Furthermore, because it utilizes characteristics that clearly distinguish each individual, it provides both a high level of security and convenience.
Biometric technologies include fingerprint recognition, facial recognition, iris recognition, vein recognition, and voice recognition, each with its own areas of application and distinct advantages and disadvantages. Among these, iris recognition is regarded as a leading biometric technology that offers high accuracy because it relies on the unique iris patterns found in every individual.
While iris recognition initially garnered significant attention when it was implemented in some smartphones, facial recognition and fingerprint recognition have now become the primary authentication methods for smartphones. On the other hand, iris recognition continues to be utilized as a critical biometric technology in access control systems, financial security, research facilities, and public institutions—where high accuracy is required.
Why is the iris suitable for biometric authentication?
The iris is the part of the eye that surrounds the black pupil. Composed of muscles, the iris acts as a diaphragm, regulating the size of the pupil to control the amount of light entering the eye.
A person’s iris forms during the fetal stage, and its unique pattern is established during the growth process. It is known to maintain virtually the same form throughout a person’s lifetime, barring specific diseases or severe damage.
Since the iris pattern is formed by the combined influence of genetic factors and environmental factors during development, even identical twins have different iris patterns. Furthermore, the left and right eyes also have different patterns, and because the iris is located inside the cornea, it is relatively unaffected by the external environment.
Thanks to these characteristics—that each person has a unique pattern that remains stable over a long period—the iris is used as a highly reliable form of biometric data for personal identification.
How does iris recognition work?
Iris recognition works by capturing a digital image of each person’s unique iris pattern, analyzing it to convert it into data, and then comparing it to previously registered information. Because the iris has a unique pattern for each person and remains virtually unchanged throughout a person’s lifetime, it offers a very high level of accuracy. Additionally, since authentication can be performed without direct skin contact, it is hygienic and highly convenient for users.
To begin iris recognition, an image of the eye is first captured with a camera. The captured image is then processed to precisely identify the area where the iris is located. During this process, non-iris areas—such as the boundary between the iris and the pupil, the boundary between the iris and the sclera, and the eyelids and eyebrows—are distinguished, and only the iris area to be used for actual analysis is extracted.
The extracted iris area is normalized into a consistent format before analysis. Since a person’s pupil dilates or constricts depending on ambient light, the shape of the iris may vary slightly depending on the shooting environment, even for the same person. Therefore, the iris recognition system compensates for these variations by transforming the image so that comparisons can always be made using the same standard.
Once normalization is complete, the iris is divided into several segments for analysis. Various features—such as the iris’s brightness and texture, the shape of its ridges, and variations in its patterns—are extracted from each region, and these features are converted into digital data that a computer can compare. This data is generally referred to as an “iris template.” Since only the iris’s features are quantified and stored—rather than the original image itself—storage space is used efficiently, and this approach also offers advantages in terms of personal information protection.
The iris template generated in this way is compared with the iris data of a registered user. The Hamming distance is typically used to determine how similar the two sets of data are. Hamming distance is a method for calculating the number of differing bits between two sets of digital data; the smaller the value, the more similar the features of the two irises are.
How is identity verified?
If the Hamming distance value resulting from the comparison of iris data is smaller than a preset threshold, the irises are deemed to belong to the same person; if it is larger than the threshold, they are deemed to belong to a different person.
This threshold is determined based on the results of statistical analysis of iris data collected from a diverse group of people. Even for the same person, the data generated is not exactly identical due to variations in the capture environment, such as shooting distance, lighting, and camera performance. In contrast, the irises of different people show much greater differences; therefore, a threshold that most effectively distinguishes between the two distributions is set to determine identity.
To improve accuracy, iris recognition systems consider both the False Rejection Rate (FRR) and the False Acceptance Rate (FAR). The FRR refers to the rate at which a legitimate user is incorrectly identified as a non-user, while the FAR refers to the rate at which a non-user is incorrectly identified as a legitimate user. By designing the system to minimize both of these errors, a high level of security and reliability is ensured.
How will iris recognition technology be utilized in the future?
So far, we have examined the characteristics of the iris and the principles of iris recognition technology.
Early iris recognition systems required near-infrared cameras and high-performance image processing devices, resulting in bulky equipment and high costs. Additionally, recognition rates could vary depending on the imaging environment, limiting their use to specific fields.
However, with significant advancements in image sensors, optical technology, AI-based image processing, and semiconductor performance, iris recognition technology has been steadily improving. Thanks to the miniaturization of cameras and the development of high-resolution image processing technology, irises can now be recognized more quickly and accurately, and both recognition speed and stability continue to improve.
Currently, iris recognition is being used more extensively in fields that require a higher level of security than smartphones. Airport automated immigration screening, financial institutions, critical national facilities, research laboratories, data centers, and medical institutions are adopting iris recognition technology to ensure high levels of security and accuracy. Furthermore, with the advancement of multimodal biometrics—which combines multiple biometric data points—there has been an increase in cases where facial recognition, fingerprint recognition, vein recognition, and iris recognition are used together.
Recently, with the integration of artificial intelligence, active research is underway to minimize the effects of varying lighting conditions, the wearing of glasses, and capture angles. Furthermore, liveness detection technology—which verifies that the eye belongs to a real person—has also advanced, continuously improving the ability to block authentication bypass attempts using photographs, videos, or artificial eyes.
Conclusion
Biometric technology is a leading security technology that verifies identity using physical characteristics unique to each individual. Among these, the iris—which has a pattern unique to each person and remains virtually unchanged throughout a person’s lifetime—offers a very high level of accuracy.
Iris recognition verifies identity by analyzing an image of the iris captured by a camera, converting its features into digital data, and comparing them with registered information. Various image processing technologies and statistical analysis techniques are utilized in this process, ensuring a high level of security and reliability.
Today, advances in artificial intelligence and image processing technology are further expanding the accuracy and scope of iris recognition. Going forward, iris recognition is expected to be utilized as a core security technology in various fields—such as finance, healthcare, public services, and access control—where personal information protection and identity verification are critical, often in combination with other biometric technologies.
