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La reconnaissance d'images est un domaine de recherche qui a été largement étudié par la communauté scientifique. Les travaux proposés dans ce cadre s'adressent principalement aux diverses applications des systèmes de vision par ordinateur et à la catégorisation des images issues de plusieurs sources. Dans cette thèse, on s'intéresse particulièrement aux systèmes de reconnaissance d'images par le contenu dans les bases hétérogènes. Les images dans ce type de bases appartiennent à différents concepts et représentent un contenu hétérogène. Pour ce faire, une large description permettant d'assurer une représentation fiable est souvent requise. Cependant, les caractéristiques extraites ne sont pas nécessairement toutes appropriées pour la discrimination des différentes classes d'images qui existent dans une base donnée d'images. D'où, la nécessité de sélection des caractéristiques pertinentes selon le contenu de chaque base. Dans ce travail, une méthode originale de sélection adaptative est proposée. Cette méthode permet de considérer uniquement les caractéristiques qui sont jugées comme les mieux adaptées au contenu de la base d'image utilisée. Par ailleurs, les caractéristiques sélectionnées ne disposent pas généralement des mêmes performances. En conséquence, l'utilisation d'un algorithme de classification, qui s'adapte aux pouvoirs discriminants des différentes caractéristiques sélectionnées par rapport au contenu de la base d'images utilisée, est vivement recommandée. Dans ce contexte, l'approche d'apprentissage par noyaux multiples est étudiée et une amélioration des méthodes de pondération des noyaux est présentée. Cette approche s'avère incapable de décrire les relations non-linéaires des différents types de description. Ainsi, nous proposons une nouvelle méthode de classification hiérarchique multi-modèles permettant d'assurer une combinaison plus flexible des caractéristiques multiples. D'après les expérimentations réalisées, cette nouvelle méthode de classification assure des taux de reconnaissance très intéressants. Enfin, les performances de la méthode proposée sont mises en évidence à travers une comparaison avec un ensemble d'approches cité dans la littérature récente du domaine. / Image recognition is widely studied by the scientific community. The proposed research in this field is addressed to various applications of computer vision systems and multiple source image categorization. This PhD dissertation deals particularly with content based image recognition systems in heterogeneous databases. Images in this kind of databases belong to different concepts and represent a heterogeneous content. In this case and to ensure a reliable representation, a broad description is often required. However, the extracted features are not necessarily always suitable for the considered image database. Hence, the need of selecting relevant features based on the content of each database. In this work, an adaptive selection method is proposed. It considers only the most adapted features according to the used image database content. Moreover, selected features do not have generally the same performance degrees. Consequently, a specific classification algorithm which considers the discrimination powers of the different selected features is strongly recommended. In this context, the multiple kernel learning approach is studied and an improved kernel weighting method is presented. It proved that this approach is unable to describe the nonlinear relationships of different description kinds. Thus, we propose a new hierarchical multi-model classification method able to ensure a more flexible combination of multiple features. Experimental results confirm the effectiveness and the robustness of this new classification approach. In addition, the proposed method is very competitive in comparison with a set of approaches cited in the recent literature.

The concept of an Image Difference Spectrum, a novel tool for the extraction of global image information, is introduced. It is shown that Image Difference Spectra are fast alternatives to granulometric curves, also referred to as pattern spectra. Image Difference Spectra are computationally easy to implement and are suitable for real-time applications.

ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, Nevada / Often it is necessary to retrieve segments of video with certain characteristics, or features, from a large archive of footage. This paper discusses how image processing algorithms can be used to automatically create a relational database, which indexes the video archive. This feature extraction can be performed either upon acquisition or in post processing. The database can then be queried to quickly locate and recover video segments with certain specified key features

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We propose a scalable and fexible hardware architecture for the extraction of image features, used in conjunction with an attentional cascade classifier for appearance-based object detection. Individual feature processors calculate feature-values in parallel, using parameter-sets and image data that is distributed via BRAM buffers. This approach can provide high utilization- and throughput-rates for a cascade classifier. Unlike previous hardware implementations, we are able to flexibly assign feature processors to either work on a single- or multiple image windows in parallel, depending on the complexity of the current cascade stage. The core of the architecture was implemented in the form of a streaming based FPGA design, and validated in simulation, synthesis, as well as via the use of a Logic Analyser for the verification of the on-chip functionality. For the given implementation, we focused on the design of Haar-like feature processors, but feature processors for a variety of heterogenous feature types, such as Gabor-like features, can also be accomodated by the proposed hardware architecture.

Master of Science / Department of Computing and Information Sciences / William H. Hsu / The goal of my project is to summarize large volumes of data and help users to visualize how events have unfolded over time. I address the problem of extracting overview terms from a time-tagged corpus of data and discuss some previous work conducted in this area. I use a statistical approach to automatically extract key terms, form groupings of related terms, and display the resultant groups on a timeline. I use a static corpus composed of news stories, as opposed to an on-line setting where continual additions to the corpus are being made. Terms are extracted using a Named Entity Recognizer, and importance of a term is determined using the [superscript]X[superscript]2 measure. My approach does not address the problem of associating time and date stamps with data, and is restricted to corpora that been explicitly tagged. The quality of results obtained is gauged subjectively and objectively by measuring the degree to which events known to exist in the corpus were identified by the system.

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Circuit breaker is an important interrupting device in power system network. It usually has a lifetime about 20 to 40 years. During breaker's service time, maintenance and inspection are imperative duties to achieve its reliable operation. To automate the diagnostic practice for circuit breaker operation and reduce the utility company's workload, Wavelet based analysis software of circuit breaker operation is developed here. Combined with circuit breaker monitoring system, the analysis software processes the original circuit breaker information, speeds up the analysis time and provides stable and consistent evaluation for the circuit breaker operation.