<p>An image that has been subject to the out-of-focus phenomenon has reducedsharpness, contrast and level of detail depending on the amount of defocus. Torestore out-of-focused images is a complex task due to the information loss thatoccurs. However there exist many restoration algorithms that attempt to revertthis defocus by estimating a noise model and utilizing the point spread function.The purpose of this thesis, proposed by FLIR Systems, was to find a robustalgorithm that can restore focus and from the customer’s perspective be userfriendly. The thesis includes three implemented algorithms that have been com-pared to MATLABs built-in. Three image series were used to evaluate the limitsand performance of each algorithm, based on deblurring quality, implementationcomplexity, computation time and usability.Results show that the Alternating Direction Method for total variation de-convolution proposed by Tao et al. [29] together with its the modified discretecosines transform version restores the defocused images with the highest qual-ity. These two algorithms include features such as, fast computational time, fewparameters to tune and a powerful noise reduction.</p>

An image that has been subject to the out-of-focus phenomenon has reducedsharpness, contrast and level of detail depending on the amount of defocus. Torestore out-of-focused images is a complex task due to the information loss thatoccurs. However there exist many restoration algorithms that attempt to revertthis defocus by estimating a noise model and utilizing the point spread function.The purpose of this thesis, proposed by FLIR Systems, was to find a robustalgorithm that can restore focus and from the customer’s perspective be userfriendly. The thesis includes three implemented algorithms that have been com-pared to MATLABs built-in. Three image series were used to evaluate the limitsand performance of each algorithm, based on deblurring quality, implementationcomplexity, computation time and usability.Results show that the Alternating Direction Method for total variation de-convolution proposed by Tao et al. [29] together with its the modified discretecosines transform version restores the defocused images with the highest qual-ity. These two algorithms include features such as, fast computational time, fewparameters to tune and a powerful noise reduction.

In augmented reality, information is often distributed between real and virtual contexts, and often appears at different distances from the viewer. This raises the issues of (1) context switching, when attention is switched between real and virtual contexts, (2) focal distance switching, when the eye accommodates to see information in sharp focus at a new distance, and (3) transient focal blur, when information is seen out of focus, during the time interval of focal distance switching. This dissertation research has quantified the impact of context switching, focal distance switching, and transient focal blur on human performance and eye fatigue in both monocular and binocular viewing conditions. Further, this research has developed a novel font that when seen out-of-focus looks sharper than standard fonts. This SharpView font promises to mitigate the effect of transient focal blur. Developing this font has required (1) mathematically modeling out-of-focus blur with Zernike polynomials, which model focal deficiencies of human vision, (2) developing a focus correction algorithm based on total variation optimization, which corrects out-of-focus blur, and (3) developing a novel algorithm for measuring font sharpness. Finally, this research has validated these fonts through simulation and optical camera-based measurement. This validation has shown that, when seen out of focus, SharpView fonts are as much as 40 to 50% sharper than standard fonts. This promises to improve font legibility in many applications of augmented reality.

Le phénomène de givrage qui se produit durant les vols d’aéronefs, lors de leurs traversées de la troposphère (zone dans laquelle la température peut descendre jusqu’à -60°C) se manifeste par une accrétion de glace sur différentes parties de l’appareil (voilures, réacteurs, sondes de mesure…) mettant en péril la sécurité de celui-ci. Ce phénomène constitue alors une problématique majeure pour la sécurité de l’aviation civile, c’est pourquoi il est nécessaire de développer de nouvelles techniques de mesure afin de détecter et d’éviter les zones à risques. Notre intérêt s’est porté sur l’imagerie interférométrique en défaut de mise au point, une technique optique offrant de nombreux avantages (large champ de mesure, gamme de tailles étudiée étendue [50 μm : quelques millimètres], distance particule/appareil de mesure de plusieurs dizaines de centimètres…). Au cours de ces travaux de thèse, nous avons développé un dispositif d’Imagerie Interférométrique de Particules (IIP) multi-vues permettant de caractériser les cristaux de glace en suspension dans latroposphère. En effet, par comparaison avec des mesures obtenues sur des images nettesenregistrées simultanément, nous avons validé l’utilisation de l’IIP multi-vues pour l’estimation dedimensions de particules de glace avec un taux d’erreur inférieur à 20%. Nous avons égalementproposé différentes approches permettant d’estimer les volumes des particules de glace et mis enévidence la « signature » typique d’une gouttelette en cours de givrage à partir d’images d’IIP.Dans une seconde partie, nous avons validé l’utilisation de l’IIP multi-vues pour le cas complexe oùles interférogrammes d’une paire de particules de glace proches l’une de l’autre se recouvrent etdiscuté des phénomènes de Moiré qui peuvent apparaître et perturber nos mesures. En outre, nousavons étendu le domaine d’utilisation de l’IIP à des milieux moins dilués. Enfin, dans une dernière partie, nous avons développé un dispositif expérimental innovant nous permettant d’effectuer des mesures d’IIP expérimentales à partir de particules « programmées » sur une matrice de micro-miroirs (DMD). / The icing phenomenon that occurs during aircraft flights during their troposphere crossings (an area where the temperature can drop to -60 ° C) is manifested by an accretion of ice on different parts of the apparatus (wings, reactors, measurement probes ...) endangering the safety of this latter. This phenomenon is therefore a major problem for the safety of civil aviation, that's why it is necessary to develop new measurement techniques to detect and avoid risk's areas. Our interest has been on interferometric out-of-focus imaging, an optical technique offering many advantages (wide measurement field, range of studied sizes extended [50 μm: a few millimeters], distance particle / measuring device several tens of centimeters ...). During this thesis, we have developed a multi-view Interferometric Particle Imaging (IPI) device to characterize suspended ice crystals in the troposphere. Indeed, by comparison with measurements obtained on in-focus images recorded simultaneously, we have validated the use of multi-view IIP for the estimation of ice particle dimensions with an error rate lower than 20%. We also proposed different approaches to estimate ice particle volumes and highlighted the typical "signature" of a droplet during icing from IIP images.In a second part, we validated the use of multi-view IIP for the complex case where the interferograms of a pair of ice particles close to each other overlap and discuss about Moiré phenomena that may appear and disrupt our measurements. In addition, we have extended the field of use of IIP to less diluted media. Finally, in the last part, we have developed an innovative experimental device allowing us to perform experimental IIP measurements from particles "programmed" on a matrix of micro-mirrors (DMD : Digital Micromirror Device).