Iris Indexing Techniques: A Review <s> INTRODUCTION <s> A wide variety of systems requires reliable personal recognition schemes to either confirm or determine the identity of an individual requesting their services. The purpose of such schemes is to ensure that the rendered services are accessed only by a legitimate user and no one else. Examples of such applications include secure access to buildings, computer systems, laptops, cellular phones, and ATMs. In the absence of robust personal recognition schemes, these systems are vulnerable to the wiles of an impostor. Biometric recognition, or, simply, biometrics, refers to the automatic recognition of individuals based on their physiological and/or behavioral characteristics. By using biometrics, it is possible to confirm or establish an individual's identity based on "who she is", rather than by "what she possesses" (e.g., an ID card) or "what she remembers" (e.g., a password). We give a brief overview of the field of biometrics and summarize some of its advantages, disadvantages, strengths, limitations, and related privacy concerns. <s> BIB001 </s> Iris Indexing Techniques: A Review <s> INTRODUCTION <s> This survey covers the historical development and current state of the art in image understanding for iris biometrics. Most research publications can be categorized as making their primary contribution to one of the four major modules in iris biometrics: image acquisition, iris segmentation, texture analysis and matching of texture representations. Other important research includes experimental evaluations, image databases, applications and systems, and medical conditions that may affect the iris. We also suggest a short list of recommended readings for someone new to the field to quickly grasp the big picture of iris biometrics. <s> BIB002
Traditionally, identification of a genuine person was based on key, password, magnetic or chip card. However, all of these can be stolen, forgotten or forged and hence password and token-based recognition systems are nowadays replaced by biometric recognition system. Even in some systems where password and token are still used, on top of it a biometric layer is added for more secure authentication. Hence there is a tremendous growth in biometric based identification system in almost all paths round the world. Biometric includes reference to the measurement, analysis, classification, science of personal recognition and verification or identification by using distinguishable biological (physiological) or behavioral trait, features or characteristic of that person. Biometric identification is the process of associating an identity to the input biometric data by comparing it against the enrolled identities in a database BIB001 . Depending on the mode of application biometric system operate on verification or identification mode. In verification mode, the system validates a person's identity by comparing the captured biometric data with their own biometric template stored in the database; say by 1:1 matching. In identification mode, the system recognizes the person by searching the template of all the users in the database, where 1: N matching is performed. Any biometric system should posses the characteristics such as: versatility, uniqueness, permanence, measurability, performance, acceptability and circumvention. Some of the commonly used physical or behavioural traits are: face, fingerprint, palm print, hand geometry, iris, keystroke, signature, voice and gait. Apart from these, there are also some traits which are used to identify a person uniquely based on odour, tongue, ear, knuckle print. Among the various biometric traits, 'iris' is proved to be a predominant and popular biometric feature for authentication and identification with a high degree of accuracy and distinctiveness. The finger print has also received substantial concentration and is being effectively used in many applications over one hundred years. Face and speech have also been extensively studied over 25 years, whereas, 'iris recognition' is a newly emerging trait in personal identification and is reported to be the most reliable biometric trait in identification and authentication BIB002 . The performance of the identification system depends more on the search space and the accuracy rate. Existing systems are till now small-scaled, databases and henceforth identifying an imposter is not a difficult task, but, as the size grows it is necessary to identify a methodology which can search the correct person with in the stipulated time. Hence, 'indexing' becomes vital to identify the legitimate person from databases based on the templates stored. The paper is organized as follows. The anatomy of the human iris and the feature extraction are described in section 2. An exhaustive survey on various indexing techniques based on the iris features are detailed in section 3. Performance metric used to evaluate the techniques and description about the databases has been reviewed in section 4. A comparative study on the performance of the indexing technique in the survey is analyzed in the last section.