The Removal of Specular Reflection in Noisy Iris Image

Iris recognition is a biometric system that uses human iris features to determine and verify the identity of human. Other biometric systems are fingerprint, face, ear, voice, gait, blood vessels and many more. A complete iris recognition system includes: iris acquisition, iris segmentation, feature extraction and matching. The main factor to obtain high segmentation and recognition accuracy is the quality of iris pattern. The quality of iris pattern can be affected because of specular reflection. Specular reflection happens during iris acquisition and it can reduce the features of iris pattern. This work is significant since the improved iris pattern can enhance the performance of iris localization, iris segmentation and feature extraction in the iris recognition system. In this paper, the iris image enhancement methods are proposed to remove the specular reflection. UBIRIS v1 and CASIA v4 databases are used for testing. Based on the results, the proposed methods managed to remove the specular reflection without affecting the iris image quality. The proposed methods also obtained fast execution time and low memor

Technical Translation: A Translation Proposal for a Photography Guide

My objective of this thesis is to propose a technical translation from English into Italian of a photography user guide in order to highlight the main challenges a technical translator may face while translating such a complex genre of writing. The source text I have decided to translate is a section taken from David Busch’s Canon EOS 80d Guide to Digital SLR Photography and focused on photography exposure. Explaining the functions of the camera’s basic controls and relating each feature to specific photographic techniques or situations, this guide provides step by step directions to learn how to use this camera properly. My idea for this work was born from both my growing interest in translation and in digital photography, a specialised field which I have always been passionate about. First, I will give a definition of what technical translation is, explaining the difference between Scientific and Technical translation, contrasting some misconceptions about technical translation and proving its importance. In order to understand how translation theory could be useful in technical translation, I will give an overview of some of its approaches and finally, I will deal with the most important features of the technical discourse. Before proposing the actual translation, the second chapter will open with an analysis of the camera user guide, which describes the intended readers, purpose, textual organization, language and register. Subsequently, I will introduce my translation method, based on the creation of a corpus and of a glossary that were used as a reference during the translation process. My thesis concludes with a commentary on the translation: I will start from some considerations about terminology, register and textual organization, to finish with some observations about cultural specificity, in order to outline the different strategies that were adopted to face some difficulties encountered during the translation process.My objective of this thesis is to propose a technical translation from English into Italian of a photography user guide in order to highlight the main challenges a technical translator may face while translating such a complex genre of writing. The source text I have decided to translate is a section taken from David Busch’s Canon EOS 80d Guide to Digital SLR Photography and focused on photography exposure. Explaining the functions of the camera’s basic controls and relating each feature to specific photographic techniques or situations, this guide provides step by step directions to learn how to use this camera properly. My idea for this work was born from both my growing interest in translation and in digital photography, a specialised field which I have always been passionate about. First, I will give a definition of what technical translation is, explaining the difference between Scientific and Technical translation, contrasting some misconceptions about technical translation and proving its importance. In order to understand how translation theory could be useful in technical translation, I will give an overview of some of its approaches and finally, I will deal with the most important features of the technical discourse. Before proposing the actual translation, the second chapter will open with an analysis of the camera user guide, which describes the intended readers, purpose, textual organization, language and register. Subsequently, I will introduce my translation method, based on the creation of a corpus and of a glossary that were used as a reference during the translation process. My thesis concludes with a commentary on the translation: I will start from some considerations about terminology, register and textual organization, to finish with some observations about cultural specificity, in order to outline the different strategies that were adopted to face some difficulties encountered during the translation process

Telerobotic rendezvous and docking vision system architecture

This research program has successfully demonstrated a new target label architecture that allows a microcomputer to determine the position, orientation, and identity of an object. It contains a CAD-like database with specific geometric information about the object for approach, grasping, and docking maneuvers. Successful demonstrations were performed selecting and docking an ORU box with either of two ORU receptacles. Small, but significant differences were seen in the two camera types used in the program, and camera sensitive program elements have been identified. The software has been formatted into a new co-autonomy system which provides various levels of operator interaction and promises to allow effective application of telerobotic systems while code improvements are continuing

Generalising the ideal pinhole model to multi-pupil imaging for depth recovery

This thesis investigates the applicability of computer vision camera models in recovering depth information from images, and presents a novel camera model incorporating a modified pupil plane capable of performing this task accurately from a single image. Standard models, such as the ideal pinhole, suffer a loss of depth information when projecting from the world to an image plane. Recovery of this data enables reconstruction of the original scene as well as object and 3D motion reconstruction. The major contributions of this thesis are the complete characterisation of the ideal pinhole model calibration and the development of a new multi-pupil imaging model which enables depth recovery. A comprehensive analysis of the calibration sensitivity of the ideal pinhole model is presented along with a novel method of capturing calibration images which avoid singularities in image space. Experimentation reveals a higher degree of accuracy using the new calibration images. A novel camera model employing multiple pupils is proposed which, in contrast to the ideal pinhole model, recovers scene depth. The accuracy of the multi-pupil model is demonstrated and validated through rigorous experimentation. An integral property of any camera model is the location of its pupil. To this end, the new model is expanded by generalising the location of the multi-pupil plane, thus enabling superior flexibility over traditional camera models which are confined to positioning the pupil plane to negate particular aberrations in the lens. A key step in the development of the multi-pupil model is the treatment of optical aberrations in the imaging system. The unconstrained location and configuration of the pupil plane enables the determination of optical distortions in the multi-pupil imaging model. A calibration algorithm is proposed which corrects for the optical aberrations. This allows the multi-pupil model to be applied to a multitude of imaging systems regardless of the optical quality of the lens. Experimentation validates the multi-pupil model’s accuracy in accounting for the aberrations and estimating accurate depth information from a single image. Results for object reconstruction are presented establishing the capabilities of the proposed multi-pupil imaging model

Theoretical and experimental study of tunable liquid crystal lenses : wavefront optimization

Adaptive optical systems have applications in various domains: imaging (zoom and autofocus), medicine (endoscopy, ophthalmology), virtual and augmented reality. Liquid crystal-based lenses have become a big part of adaptive optics industry as they have numerous advantages in comparison with traditional methods. Despite significant progress made over the past decades, certain performance and production limitations still exist. This thesis explores ways of overcoming these problems, considering two types of tunable lenses: liquid crystal lens using dielectric dividing principle and modal control lens.The introduction of this thesis presents the theory of liquid crystals and adaptive lenses, addressing existing liquid crystal lenses as well.In the first and second chapters of this work we demonstrate the results of theoretical modeling of double dielectric optically hidden liquid crystal lens design. We have studied the influence of geometrical parameters, such as thickness of liquid crystal cell, shape and dimensions of dielectrics forming the optically hidden layer, on the optical power of the lens. The dependences of optical power on the relative permittivity and conductivity of dielectrics were obtained. The behavior of such a lens in the presence of temperature variation was analyzed. We have further extended the concept of hidden dielectric layer to exploration of microstructures. Two systems of microlenses and microprisms have been simulated. The comparison of optical phase modulation dependence on spatial frequency of microstructures was obtained. Deviations from ideal wavefronts were evaluated in both cases. We also compared proposed designs with a standard interdigital electrode approach. Suggested devices could be used for continuous light steering or as tunable microlens arrays. In the third and fourth chapters we present our studies of tunable lenses based on modal control principle. We verified simulation results by comparing them with experimentally obtained dependences of optical power and root mean square spherical aberrations. We have explored the following modifications of conventional modal control lens: 1) additional powered ring electrode; 2) floating disk electrode; 3) combination of the first two cases. The influence of each modification was studied and explained. Simulation results showed that using the combination of additional electrodes along with optimal powering technique -the wavefront could be corrected within the entire clear aperture of the lens. Modified lens meets low aberration requirements for ophthalmic applications (for example,intraocular implant). Finally, a new design of a wide aperture tunable modal control Fresnel lens was investigated. Imaging performance of the proposed Fresnel lens was evaluated and compared with the reference lens built using traditional modal control approach. The prototype device demonstrated the increase of optical powerin comparison with a conventional modal control lens of the same aperture size. A theoretical model and numerical simulations of the Fresnel lens design were presented. Simulations demonstrated a possibility of noticeable image quality improvement obtained using optimized voltages and frequencies

Development of a miniaturized microscope for depth-scanning imaging at subcellular resolution in freely behaving animals

Le fonctionnement du cerveau humain est fascinant. En seulement quelques millisecondes, des milliards de neurones synchronisés perçoivent, traitent et redirigent les informations permettant le contrôle de notre corps, de nos sentiments et de nos pensées. Malheureusement, notre compréhension du cerveau reste limitée et de multiples questions physiologiques demeurent. Comment sont exactement reliés le fonctionnement neuronal et le comportement humain ? L’imagerie de l’activité neuronale au moyen de systèmes miniatures est l’une des voies les plus prometteuses permettant d’étudier le cerveau des animaux se déplaçant librement. Cependant, le développement de ces outils n’est pas évident et de multiples compromis techniques doivent être faits pour arriver à des systèmes suffisamment petits et légers. Les outils actuels ont donc souvent des limitations concernant leurs caractéristiques physiques et optiques. L’un des problèmes majeur est le manque d’une lentille miniature électriquement réglable et à faible consommation d’énergie permettant l’imagerie avec un balayage en profondeur. Dans cette thèse, nous proposons un nouveau type de dispositif d’imagerie miniature qui présente de multiples avantages mécaniques, électriques et optiques par rapport aux systèmes existants. Le faible poids, la petite dimension, la capacité de moduler électriquement la distance focale à l’aide d’une lentille à cristaux liquides (CL) et la capacité d’imager des structures fines sont au cœur des innovations proposées. Dans un premier temps, nous présenterons nos travaux (théoriques et expérimentaux) de conception, assemblage et optimisation de la lentille à CL accordable (TLCL, pour tunable liquid crystal lens). Deuxièmement, nous présenterons la preuve de concept macroscopique du couplage optique entre la TLCL et la lentille à gradient d’indice (GRIN, pour gradient index) en forme d’une tige. Utilisant le même système, nous démontrerons la capacité de balayage en profondeur dans le cerveau des animaux anesthésiés. Troisièmement, nous montrerons un dispositif d’imagerie (2D) miniature avec de nouvelles caractéristiques mécaniques et optiques permettant d’imager de fines structures neuronales dans des tranches de tissus cérébraux fixes. Enfin, nous présenterons le dispositif miniaturisé, avec une TLCL intégrée. Grâce à notre système, nous obtenons ≈ 100 µm d’ajustement électrique de la profondeur d’imagerie qui permet d’enregistrer l’activité de fines structures neuronales lors des différents comportements (toilettage, marche, etc.) de la souris.The functioning of the human brain is fascinating. In only a few milliseconds, billions of finely tuned and synchronized neurons perceive, process and exit the information that drives our body, our feelings and our thoughts. Unfortunately, our understating of the brain is limited and multiple physiological questions remain. How exactly are related neural functioning and human behavior ? The imaging of the neuronal activity by means of miniaturized systems is one of the most promising avenues allowing to study the brain of the freely moving subjects. However, the development of these tools is not obvious and multiple technical trade-offs must be made to build a system that is sufficiently small and light. Therefore, the available tools have different limitations regarding their physical and optical characteristics. One of the major problems is the lack of an electrically adjustable and energy-efficient miniature lens allowing to scan in depth. In this thesis, we propose a new type of miniature imaging device that has multiple mechanical, electrical and optical advantages over existing systems. The low weight, the small size, the ability to electrically modulate the focal distance using a liquid crystal (LC) lens and the ability to image fine structures are among the proposed innovations. First, we present our work (theoretical and experimental) of design, assembling and optimization of the tunable LC lens (TLCL). Second, we present the macroscopic proof-of-concept optical coupling between the TLCL and the gradient index lens (GRIN) in the form of a rod. Using the same system, we demonstrate the depth scanning ability in the brain of anaesthetized animals. Third, we show a miniature (2D) imaging device with new mechanical and optical features allowing to image fine neural structures in fixed brain tissue slices. Finally, we present a state-of-the-art miniaturized device with an integrated TLCL. Using our system, we obtain a ≈ 100 µm electrical depth adjustment that allows to record the activity of fine neuronal structures during the various behaviours (grooming, walking, etc.) of the mouse

Facial Biometrics on Mobile Devices: Interaction and Quality Assessment

Biometric face recognition is a quick and convenient security method that allows unlocking a smartphone device without the need to remember a PIN code or a password. However, the unconstrained mobile environment brings considerable challenges in facial verification performance. Not only the verification but also the enrolment on the mobile device takes place in unpredictable surroundings. In particular, facial verification involves the enrolment of unsupervised users across a range of environmental conditions, light exposure, and additional variations in terms of user's poses and image background. Is there a way to estimate the variations that a mobile scenario introduces over the facial verification performance? A quality assessment can help in enhancing the biometric performance, but in the context of mobile devices, most of the standardised requirements and methodology presented are based on passport scenarios. A comprehensive analysis should be performed to assess the biometric performance in terms of image quality and user interaction in the particular context of mobile devices. This work aimed to contribute to improving the performance and the adaptability of facial verification systems implemented on smartphones. Fifty-three participants were asked to provide facial images suitable for face verification across several locations and scenarios. A minimum of 150 images per user was collected with a smartphone camera within three different sessions. Sensing data was recorded to assess user interaction during the biometric presentation. Images were also recorded using a Single Lens Reflex camera to enable a comparison with conditions similar to a passport scenario. Results showed the relationship within five selected quality metrics commonly used for quality assessment and the variables introduced by the environment, the user and the camera. Innovative methodologies were also proposed to assess the user interaction using sensors implemented in the smartphone. The analysis underlined important issues and formulated useful observations to enhance facial verification performance on smartphone devices