This dissertation develops an innovative approach towards less-constrained iris biometrics. Two major contributions are made in this research endeavor: (1) Designed an award-winning segmentation algorithm in the less-constrained environment where image acquisition is made of subjects on the move and taken under visible lighting conditions, and (2) Developed a pioneering iris biometrics method coupling segmentation and recognition of the iris based on video of moving persons under different acquisitions scenarios. The first part of the dissertation introduces a robust and fast segmentation approach using still images contained in the UBIRIS (version 2) noisy iris database. The results show accuracy estimated at 98% when using 500 randomly selected images from the UBIRIS.v2 partial database, and estimated at 97% in a Noisy Iris Challenge Evaluation (NICE.I) in an international competition that involved 97 participants worldwide involving 35 countries, ranking this research group in sixth position. This accuracy is achieved with a processing speed nearing real time. The second part of this dissertation presents an innovative segmentation and recognition approach using video-based iris images. Following the segmentation stage which delineats the iris region through a novel segmentation strategy, some pioneering experiments on the recognition stage of the less-constrained video iris biometrics have been accomplished. In the video-based and less-constrained iris recognition, the test or subject iris videos/images and the enrolled iris images are acquired with different acquisition systems. In the matching step, the verification/identification result was accomplished by comparing the similarity distance of encoded signature from test images with each of the signature dataset from the enrolled iris images. With the improvements gained, the results proved to be highly accurate under the unconstrained environment which is more challenging. This has led to a false acceptance rate (FAR) of 0% and a false rejection rate (FRR) of 17.64% for 85 tested users with 305 test images from the video, which shows great promise and high practical implications for iris biometrics research and system design.

A presente dissertação aborda o processo de identificação por biometria das estruturas oculares, analisando suas bases biológicas e tecnológicas e sua aplicabilidade e confiabilidade para utilização jurídica. Está dividida em três partes. Na primeira, são analisados aspectos do conceito de identidade em suas diversas acepções e do processo de identificação médico legal por meio da utilização de diferentes métodos. Na segunda, passa-se a estudar a biometria da íris e da retina, abordando suas bases biológicas e tecnológicas. Na terceira e última parte, estuda-se a aplicabilidade e confiabilidade da biometria ocular para finalidades jurídicas, como método de perícia da identidade. / The purpose of this work is to study the identification process by ocular biometrics, from its biological and technological basis to its forensic and legal system applications. It is divided into three sections. The first section discusses the concept of identity and the identification methods used by forensic professionals. The second section discusses the ocular biometrics methods using iris and retinal traits, emphasizing their biological as well as their technological basis. The third and last section discusses the reliability and applicability of these biometrics modalities as identification methods in legal and forensic issues.

A presente dissertação aborda o processo de identificação por biometria das estruturas oculares, analisando suas bases biológicas e tecnológicas e sua aplicabilidade e confiabilidade para utilização jurídica. Está dividida em três partes. Na primeira, são analisados aspectos do conceito de identidade em suas diversas acepções e do processo de identificação médico legal por meio da utilização de diferentes métodos. Na segunda, passa-se a estudar a biometria da íris e da retina, abordando suas bases biológicas e tecnológicas. Na terceira e última parte, estuda-se a aplicabilidade e confiabilidade da biometria ocular para finalidades jurídicas, como método de perícia da identidade. / The purpose of this work is to study the identification process by ocular biometrics, from its biological and technological basis to its forensic and legal system applications. It is divided into three sections. The first section discusses the concept of identity and the identification methods used by forensic professionals. The second section discusses the ocular biometrics methods using iris and retinal traits, emphasizing their biological as well as their technological basis. The third and last section discusses the reliability and applicability of these biometrics modalities as identification methods in legal and forensic issues.