Within the realm of biosensing, DNA analysis has become an indispensable research tool in medicine, enabling the investigation of relationships among genes, proteins, and drugs. Conventional DNA microarray technology uses multiple lasers and complex optics, resulting in expensive and bulky systems which are not suitable for point-of-care medical diagnostics. The immobilization of DNA probes across the microarray substrate also results in substantial spatial variation. To mitigate the above shortcomings, this thesis presents a set of techniques developed for the CMOS image sensor for point-of-care spectrally-multiplexed fluorescent DNA sensing and other fluorescence biosensing applications. First, a CMOS tunable-wavelength multi-color photogate (CPG) sensor is presented. The CPG exploits the absorption property of a polysilicon gate to form an optical filter, thus the sensor does not require an external color filter. A prototype has been fabricated in a standard 0.35μm digital CMOS technology and demonstrates intensity measurements of blue (450nm), green (520nm), and red (620nm) illumination. Second, a wide dynamic range CMOS multi-color image sensor is presented. An analysis is performed for the wide dynamic-range, asynchronous self-reset with residue readout architecture where photon shot noise is taken into consideration. A prototype was fabricated in a standard 0.35μm CMOS process and is validated in color light sensing. The readout circuit achieves a measured dynamic range of 82dB with a peak SNR of 46.2dB. Third, a low-power CMOS image sensor VLSI architecture for use with comparator based ADCs is presented. By eliminating the in-pixel source follower, power consumption is reduced, compared to the conventional active pixel sensor. A 64×64 prototype with a 10μm pixel pitch has been fabricated in a 0.35μm standard CMOS technology and validated experimentally. Fourth, a spectrally-multiplexed fluorescence contact imaging microsystem for DNA analysis is presented. The microsystem has been quantitatively modeled and validated in the detection of marker gene sequences for spinal muscular atropy disease and the E. coli bacteria. Spectral multiplexing enables the two DNA targets to be simultaneously detected with a measured detection limit of 240nM and 210nM of target concentration at a sample volume of 10μL for the green and red transduction channels, respectively.

Les technologies CMOS représentent aujourd’hui plus de 90% du marché des capteurs d’images : elles permettent d’intégrer des systèmes intelligents dans une seule puce (SoC = System-On-Chip) et ouvrent la voie à l’intégration d’algorithmes de plus en plus complexes dans les dernières générations de capteurs. Des techniques telles que la reconstruction grande dynamique nécessitent d’acquérir plusieurs images avec un même capteur et de les recombiner. Ces nouvelles contraintes nécessitent d’augmenter drastiquement le débit d’images pour des capteurs de tailles conséquentes (Jusqu'à 30 Mpixels), ainsi que d’augmenter la résolution du convertisseur analogique numérique (jusqu’à 14 bits). Cela crée une demande forte en techniques de conversion analogique-numérique. Ces techniques doivent obéir en même temps aux contraintes de performance notamment la vitesse, la résolution, le faible bruit, la faible consommation et l'intégrabilité mais aussi aux contraintes de qualité d'image impactées directement par la chaine de conversion analogique-numérique en plus de la technologie du pixel. D'ici découle une double problématique pour le sujet:- Etudier et déterminer les limites atteignables en termes de performance sur les différents axes précités.- Gestion du fonctionnement massivement parallèle lié à la structure inhérente des capteurs d'image en vue d'avoir une qualité d'image irréprochable. / CMOS technologies represent nowadays more than 90% of image sensors market given their features namely the possibility of integrating entire intelligent systems on the same chip (SoC = System-On-Chip). Thereby, allowing the implementation of more and more complex algorithms in the new generations of image sensors.New techniques have emerged like high dynamic range reconstruction which requires the acquisition of several images to build up one, thus multiplying the frame rate.These new constraints require a drastic increase of image rate for sensors ofconsiderable size (Up to 30 Mpix and more). At the same time, the ADCresolution has to be increased to be able to extract more details (until 14 bits).With all these demanding specifications, analog-to-digital conversion capabilities have to be boosted as far as possible.These capabilities can be distinguished into two main research axes representing the pillars of the PhD work, namely:+ The study of the reachable limits in terms of performance: Speed, Resolution,Low Noise, Low power consumption and small design pitch.+ The management of the highly parallel operation linked to the structure of animage sensor. Solutions have to be found so as to avoid image artefacts andpreserve the image quality.

The aim of the work was to put together the list of possible ways to use high resolution image in real estate practice. Photographies are created by stitching more than one image on itself. Further on was developed methodology of working with these images and was made an illustration with detailed description of the procedure for each individual case. For each procedure were proposed possibilities in practical using. For the thesis purposes was conducted real estate and public survey. Based on results of the survey were purposed draft measures to improve internet real estate advertising.

Master's thesis is focused on capturing of low dynamic range images using common devices such as camera and its multiple exposure. The main part of thesis is dedicated to composing these images to HDR image, inclusive sequence of images of static scenes, but also dynamic ones. Next part describes tone mapping used for display HDR image on LDR monitors. Moreover, there is given design and implementation of application solving problems mentioned earlier. In the end, the implemented application is evaluated and the possible continuation of this work is stated.

Fyzikálně přijatelné osvětlení v reálném čase je často dosaženo použitím aproximací. Současné metody často aproximují globální osvětlení v prostoru obrazu s využitím schopností moderních grafických karet. Dva techniky z této kategorie, screen-space ambient occlusion a screen-space directional occlusion jsou popsány detailněji v této práci. Screen-space directional occlusion je zobecněná verze screen-space ambient occlusion s podporou jednoho difúzního odrazu a závislostí na směrové informaci světla. Hlavním cílem projektu bylo experimentování s těmito metodami. Pro uniformní distribuci náhodných vzorek pro obě metody byla použita Halton sekvence. Pro potlačení šumu je použita bilaterální filtrace, která bere do úvahy geometrické vlastnosti scény. Metody jsou dál zrychleny použitím nižších rozlišení pro výpočet. Rekonstrukce výsledků do původní velikosti pro vytvoření konečného obrazu je realizována pomoci joint bilateral upsamplingu. Kromě metod globálního osvětlení byly v práci použity aj metody pro mapování stínů a HDR osvětlení.

The target of this thesis is sumarize the theory of metods used for composition image sequence into single high dynamic range image. Selected methods and algorithms are described in theoretical part and implemented in practical part of this thesis. It was used C++ language with using OpenCV library.

Cílem této práce je demonstrovat možnost renderování srsti přímo do existujících obrazů bez toho, aby bylo po uživateli požadováno překreslení všech pixelů nebo dodání kompletní 3D geometrie a osvětlení. Srst je přidána na povrch objektů pomocí extrakce jejich přibližného tvaru a světelných informací z obrazu a takto získaný objekt je poté přerenderován. Tento přístup je nový v tom, že vysokoúrovňové úpravy obrazu (jako např. přidání srsti), mohou úspěšně vést k vizuálně korektním výsledkům a to i přes omezení nepřesnou geometrií a světelnými podmínkami. Relativně velká množina technik použitých v této práci zahrnuje obrazy s velkým dynamickým rozsahem, metody extrakce 3D tvaru z obrazu, výsledky výzkumu vnímání tvaru a osvětlení a fotorealistické renderování. Hlavním cílem práce je potvrdit koncept popsaný výše. Hlavním implementačním jazykem bylo C++ s použitím knihoven wxWidgets, OpenGL a libTIFF. Renderování bylo realizováno v software 3Delight kompatibilním se standardem Renderman, za pomoci množiny shaderů implementovaných v nativním jazyce Rendermanu.

<p>Imaging and computer vision systems deployed in real-world environments face the challenge of accommodating a wide range of lighting conditions. However, the cost, the demand for high resolution, and the miniaturization of imaging devices impose physical constraints on sensor design, limiting both the dynamic range and effective aperture size of each pixel. Consequently, conventional CMOS sensors fail to deliver satisfactory capture in high dynamic range scenes or under photon-limited conditions, thereby impacting the performance of downstream vision tasks. In this thesis, we address two key problems: 1) exploring the utilization of spatial multiplexing, specifically spatially varying exposure tiling, to extend sensor dynamic range and optimize scene capture, and 2) developing techniques to enhance the robustness of object detection systems under photon-limited conditions.</p> <p><br></p> <p>In addition to challenges imposed by natural environments, real-world vision systems are susceptible to adversarial attacks in the form of artificially added digital content. Therefore, this thesis presents a comprehensive pipeline for constructing a robust and scalable system to counter such attacks.</p>

Cette thèse porte sur la conception, la réalisation et la caractérisation de diodes lasers de puissance, faible bruit à 1.5 µm sur InP pour des applications d’optique hyperfréquence, notamment pour des liaisons optiques analogiques de grande dynamique pour les systèmes radar. La première partie du travail a consisté à modéliser et concevoir des structures laser DFB ayant de faibles pertes internes. Ces structures, appelées lasers à semelle, incorporent une couche épaisse de matériaux entre la zone active et le substrat pour agrandir et délocaliser le mode propre optique des zones dopées p. La complexité de la conception résidait dans le bon compromis à trouver entre les performances statiques et dynamiques. Nous avons réalisé des diodes-lasers DFB avec une puissance > 150 mW, un rendement de 0.4 W/A, un niveau de bruit de 160 dB/Hz et une bande passante de modulation à 3 dB de 7.5 GHz. Les composants ont ensuite été caractérisés puis évalués dans des liaisons analogiques. Nous avons démontré des performances de gain de liaison, de dynamique et de point de compression à l’état de l’art mondial. En bande L (1-2 GHz) par exemple, nous avons montré des liaisons avec 0.5 dB de gain, un point de compression de 21 dBm et une dynamique (SFDR) de 122 dB.Hz2/3.En utilisant la même méthodologie de conception, la dernière partie du travail de thèse a été consacrée à la réalisation et à la caractérisation de lasers de puissance à verrouillage de modes pour la génération de train d’impulsions ultra-courts et la génération de peignes de fréquences. Ces structures présentent de très faibles largeurs de raie RF (550 Hz) et de très fortes puissances optiques (> 18 W en puissance crête). / This work focuses on the design, realization and characterization of high power, low noise 1.5 µm diode lasers for microwave applications and more particularly for high dynamic optical analog link for radar systems. The first part of this study deals with modeling and design of low internal losses DFB laser structures. These specific structures are called slab-coupled optical waveguide lasers, and are composed of a thick layer between the active layer and the substrate. The aim of this waveguide is to enlarge the optical eigenmode and to move the optical mode away from p-doped layers. The main difficulty was to find the good trade-off between laser static performances (optical power, efficiency) and dynamic performances (RIN and modulation bandwidth). We have succeeded in developing high efficiency (0.4 W/A), low noise (RIN ≈ 160 dB/Hz) DFB lasers with more than 150 mW and a 3 dB modulation bandwidth up to 7.5 GHz. We have then characterized our components on wide band and narrow band analog links. We have demonstrated state of the art gain links, dynamic and 1 dB compression power. In the L band (1-2 GHz) for example, we have obtained an optical link with a gain of 0.5 dB, a compression power of 21 dBm and a dynamic (SFDR) of 122 dB.Hz2/3.Finally we have applied the methodology and the design of slab-coupled optical waveguide structures to develop high power mode-locked lasers for ultra-short pulses generation and for optical and electrical comb generation. We have demonstrated narrow RF linewidth (550 Hz) lasers with very high power (continuous power > 400 mW and peak power > 18 W).

This thesis focuses on 3D computer graphics and the continuous maximisation of rendering quality and performance. Its main focus is the critical analysis of numerous real-time rendering algorithms and the construction of an empirically derived system for the high-speed rendering of shader-based special effects, lighting effects, shadows, reflection and refraction, post-processing effects and the processing of physics. This critical analysis allows us to assess the relationship between rendering quality and performance. It also allows for the isolation of key algorithmic weaknesses and possible bottleneck areas. Using this performance data, gathered during the analysis of various rendering algorithms, we are able to define a selection engine to control the real-time cycling of rendering algorithms and special effects groupings based on environmental conditions. Furthermore, as a proof of concept, to balance Central Processing Unit (CPU) and Graphic Processing Unit (GPU) load for and increased speed of execution, our selection system unifies the GPU and CPU as a single computational unit for physics processing and environmental mapping. This parallel computing system enables the CPU to process cube mapping computations while the GPU can be tasked with calculations traditionally handled solely by the CPU. All analysed and benchmarked algorithms were implemented as part of a modular rendering engine. This engine offers conventional first-person perspective input control, mesh loading and support for shader model 4.0 shaders (via Microsoft’s High Level Shader Language) for effects such as high dynamic range rendering (HDR), dynamic ambient lighting, volumetric fog, specular reflections, reflective and refractive water, realistic physics, particle effects, etc. The test engine also supports the dynamic placement, movement and elimination of light sources, meshes and spatial geometry. Critical analysis was performed via scripted camera movement and object and light source additions – done not only to ensure consistent testing, but also to ease future validation and replication of results. This provided us with a scalable interactive testing environment as well as a complete solution for the rendering of computationally intensive 3D environments. As a full-fledged game engine, our rendering engine is amenable to first- and third-person shooter games, role playing games and 3D immersive environments. Evaluation criteria (identified to access the relationship between rendering quality and performance), as mentioned, allows us to effectively cycle algorithms based on empirical results and to distribute specific processing (cube mapping and physics processing) between the CPU and GPU, a unification that ensures the following: nearby effects are always of high-quality (where computational resources are available), distant effects are, under certain conditions, rendered at a lower quality and the frames per second rendering performance is always maximised. The implication of our work is clear: unifying the CPU and GPU and dynamically cycling through the most appropriate algorithms based on ever-changing environmental conditions allow for maximised rendering quality and performance and shows that it is possible to render high-quality visual effects with realism, without overburdening scarce computational resources. Immersive rendering approaches used in conjunction with AI subsystems, game networking and logic, physics processing and other special effects (such as post-processing shader effects) are immensely processor intensive and can only be successfully implemented on high-end hardware. Only by cycling and distributing algorithms based on environmental conditions and through the exploitation of algorithmic strengths can high-quality real-time special effects and highly accurate calculations become as common as texture mapping. Furthermore, in a gaming context, players often spend an inordinate amount of time fine-tuning their graphics settings to achieve the perfect balance between rendering quality and frames-per-second performance. Using this system, however, ensures that performance vs. quality is always optimised, not only for the game as a whole but also for the current scene being rendered – some scenes might, for example, require more computational power than others, resulting in noticeable slowdowns, slowdowns not experienced thanks to our system’s dynamic cycling of rendering algorithms and its proof of concept unification of the CPU and GPU. / Thesis (PhD)--University of Pretoria, 2012. / Computer Science / unrestricted