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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Combining aesthetics and perception for display retargeting / Méthodes de display retargeting basées sur l'intention artistique et les caractéristiques perceptuelles

Bist, Cambodge 23 October 2017 (has links)
Cette thèse présente des contributions sur différents aspects du ''display retargeting'' dans le cadre de l'imagerie HDR (pour High Dynamic Range imaging en anglais). Bien que les contributions soient diverses, elles sont motivées par notre conviction que la préservation de l'intention artistique et la prise en compte de caractéristiques en termes de perception du système visuel humain sont essentielles pour un ''display retargeting'' esthétiquement et visuellement confortable. / This thesis presents various contributions in display retargeting under the vast field of High Dynamic Range (HDR) imaging. The motivation towards this work is the conviction that by preserving artistic intent and considering insights from human visual system leads to aesthetic, comfortable and efficient display retargeting.
2

Increasing temporal, structural, and spectral resolution in images using exemplar-based priors

Holloway, Jason 16 September 2013 (has links)
In the past decade, camera manufacturers have offered smaller form factors, smaller pixel sizes (leading to higher resolution images), and faster processing chips to increase the performance of consumer cameras. However, these conventional approaches have failed to capitalize on the spatio-temporal redundancy inherent in images, nor have they adequately provided a solution for finding $3$D point correspondences for cameras sampling different bands of the visible spectrum. In this thesis, we pose the following question---given the repetitious nature of image patches, and appropriate camera architectures, can statistical models be used to increase temporal, structural, or spectral resolution? While many techniques have been suggested to tackle individual aspects of this question, the proposed solutions either require prohibitively expensive hardware modifications and/or require overly simplistic assumptions about the geometry of the scene. We propose a two-stage solution to facilitate image reconstruction; 1) design a linear camera system that optically encodes scene information and 2) recover full scene information using prior models learned from statistics of natural images. By leveraging the tendency of small regions to repeat throughout an image or video, we are able to learn prior models from patches pulled from exemplar images. The quality of this approach will be demonstrated for two application domains, using low-speed video cameras for high-speed video acquisition and multi-spectral fusion using an array of cameras. We also investigate a conventional approach for finding 3D correspondence that enables a generalized assorted array of cameras to operate in multiple modalities, including multi-spectral, high dynamic range, and polarization imaging of dynamic scenes.
3

Imaging and Object Detection under Extreme Lighting Conditions and Real World Adversarial Attacks

Xiangyu Qu (16385259) 22 June 2023 (has links)
<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>

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