Security methods based on biometrics have been gaining importance increasingly in the last few years due to recent advances in biometrics technology and its reliability and efficiency in real world applications. Also, several major security disasters that occurred in the last decade have given a new momentum to this research area. The successful development of biometric security applications cannot only minimise such threats but may also help in preventing them from happening on a global scale. Biometric security methods take into account humans’ unique physical or behavioural traits that help to identify them based on their intrinsic characteristics. However, there are a number of issues related to biometric security, in particular with regard to surveillance images. The first issue is related to the poor visibility of the images produced by surveillance cameras and the second issue is concerned with the effective image retrieval based on user query. This research addresses both issues. This research addresses the first issue of low quality of surveillance images by proposing an integrated image enhancement approach for face detection. The proposed approach is based on contrast enhancement and colour balancing methods. The contrast enhancement method is used to improve the contrast, while the colour balancing method helps to achieve a balanced colour. Importantly, in the colour balancing method, a new process for colour cast adjustment is introduced which relies on statistical calculation. It can adjust the colour cast and maintain the luminance of the whole image at the same level. The research addresses the second issue relating to image retrieval by proposing a content-based image retrieval approach. The approach is based on the three welliii known algorithms: colour histogram, texture and moment invariants. Colour histogram is used to extract the colour features of an image. Gabor filter is used to extract the texture features and the moment invariant is used to extract the shape features of an image. The use of these three algorithms ensures that the proposed image retrieval approach produces results which are highly relevant to the content of an image query, by taking into account the three distinct features of the image and the similarity metrics based on Euclidean measure. In order to retrieve the most relevant images the proposed approach also employs a set of fuzzy heuristics to improve the quality of the results further. The integrated image enhancement approach is applied to the enhancement of low quality images produced by surveillance cameras. The performance of the proposed approach is evaluated by applying three face detection methods (skin colour based face detection, feature based face detection and image based face detection methods) to surveillance images before and after enhancement using the proposed approach. The results show a significant improvement in face detection when the proposed approach was applied. The performance of the content-based image retrieval approach is carried out using the standard Precision and Recall measures, and the results are compared with wellknown existing approaches. The results show the proposed approach perform s better than the well-known existing approaches.

[pt] Atualmente, a preocupação com segurança vem crescendo dia após dia. Vários trabalhos abordando o desenvolvimento de sistemas de supervisão já foram realizados. Esta dissertação propõe um método automático capaz de determinar o número de pessoas em uma área monitorada por uma câmera de vídeo, assim como detectar mudanças na imagem potencialmente causadas por atitudes ilícitas. Uma aplicação típica seria a segurança de galpões durante a noite, em finais de semana ou em qualquer momento onde o acesso de pessoas é permitido, mas o movimento de cargas não. Mais precisamente, a intenção é detectar se uma pessoa que está passando pelo ambiente carrega consigo um objeto pertencente ao local ou deixa um objeto no local, quando apenas o movimento de pessoas é admitido na área. Além disto, o sistema determina o número de pessoas na cena. O método consiste na aplicação de quatro etapas em seqüências de vídeo: a) separação de fundo / primeiro plano, b) atualização dinâmica da estimativa de fundo, c) localização / contagem de pessoas, e d) detecção de atitudes suspeitas. Os algoritmos de separação de fundo / primeiro plano e de estimativa de fundo toleram variações pequenas de iluminação e efeitos de sombra. Já a contagem / localização de pessoas explora informações de cor e coerência de movimento. Soluções para atender estes aspectos são encontradas na literatura, porém nenhuma delas atende todos eles juntos. O método foi avaliado por experimentos realizados através de um protótipo e apresentou resultados encorajadores. / [en] There is worldwide an increasing concern about security issues. A great deal of efforts have been undertaken in order to provide surveillance systems. This work proposes an automatic method to determine the number of people moving in an area monitored by a video camera, as well as to detect image changes, which are potentially due to illicit attitudes. A typical application is the security of warehouses during the night, on weekends or at any time when people access is allowed but no load movement is admissible. Specifically it focuses on detecting when a person passing by the environment carries any object belonging to the background away or leaves any object in the background, while only people movement is allowed in the area. Besides it estimates the number of people on scene. The method consists of performing four main tasks on video sequences: a) background and foreground separation, b) background estimative dynamic update, c) people location and counting, and d) suspicious attitudes detection. The proposed background and foreground separation and background estimative update algorithms deal with illumination fluctuation and shade effects. People location and counting explores colour information and motion coherence. Solutions meeting these requirements are proposed in the literature, but no one deals with all of them together. The method has been validated by experiments carried out on a prototype and produced encouraging results.

Apport méthodologiquepour une approche de l’analyse des discours dans l’aire germanophoneCe travail se réclame de deux domaines de recherches : la Romanistik (études des langues romanes en Allemagne, et plus précisément étude de la langue française) et l’analyse linguistique du discours française [note de bas de page 1]. Il repose sur les prémisses suivantes : malgré l'internationalisation des différents domaines scientifiques, les approches linguistiques en analyse du discours sont fortement influencées par le contexte national. Ainsi, la Romanistik n’a jamais développé de théorétisation marquante en analyse du discours au sens strict, ce qui pourrait expliquer son recours fréquent aux approches de la Germanistik (linguistique allemande). D’autre part, on peut constater que la notion de discours est très souvent définie d’après les théories philosophiques de Michel Foucault et que très peu d’autres ouvrages français sont pris en compte. Cette thèse vise à combler cette méconnaissance.De nombreux travaux en analyse linguistique du discours en France mettant l’accent sur certaines structures et/ou se focalisant sur des aspects particuliers, il s’agit de proposer un aperçu historique du développement de cette approche à partir des années 1960 et de faire connaître différentes recherches menées en France, en Suisse et en Belgique. Dans ce cadre, les notions d’« événement discursif », de « polyphonie », d’ « ethos » et de « point de vue » sont examinées. Une seule approche de la Germanistik est abordée, parce qu’elle est complémentaire, celle qui introduit la notion de « centre agonistique » (en allemand : agonale Zentren) dans le but de la mettre en relation avec celle de « point de vue » et plus généralement avec l’analyse argumentative. Le chapitre 4 constitue l’axe central du travail. Il sert à l’élaboration et à la compilation de plusieurs niveaux d’analyse : (.) [note de bas de page 2] le niveau extra-discursif, (I) le niveau prédiscursif, (II) le niveau de la scène d’énonciation, (III) le niveau thématique, (IV) le niveau des perspectives (polyphonie, argumentation, agonistique) et (V) le niveau extensif. Enfin, dans une dernière partie, on présente la mise en œuvre des propositions méthodologiques sur des corpus constitués d’articles de journaux et de magazines français, de textes radiophoniques et de weblogs. Ces textes sont organisés en trois sections en relation avec les événements retenus dans le contexte de la « sécurité » et de la « surveillance » : (1) les révélations sur le scandale d'espionnage de la NSA, (2) les attentats terroristes contre Charlie Hebdo en janvier 2015 et (3) les attaques perpétrées à Paris en novembre 2015 contre des cafés, un stade et la salle de concert du Bataclan.Note de bas de page 1: Cette configuration est rendue possible grâce à un projet de thèse de doctorat binational dans le cadre d’une cotutelle entre l’Université de Heidelberg et l’Université Paris-Est Créteil.Note de bas de page 2: Le niveau extra-discursif ne fait pas partie du compte car il ne repose pas sur des éléments linguistiques, mais il inclut des informations utiles pour l’interprétation des textes du corpus concerné. / Developing a linguistic framework for discourse analysis.An approach between paradigms of French discourse linguistics and selected impulses from German Philology illustrated with the topic of security and surveillanceThe work is anchored in two scientific fields: firstly, in German Romance studies, more precisely in French linguistics, and secondly in French linguistics in France itself.[Footnote 1] It is based on the following premises: Despite the internationalization in the different scientific fields, linguistic approaches in discourse analysis are strongly influenced by their respective national research context. Furthermore, we can observe that until today, no sophisticated theory formation exists in this domain of German Romance studies. This could be the reason why German Romance studies mostly draw on approaches from German language studies. In turn, the reception of French research in German linguistic studies is often limited to Foucault. Consequently, it seems a desideratum for German Romance Studies to not only consider the characteristics of the French language, but also the specifics of linguistic approaches to discourses.There are a multitude of elements and facets which, taken together, form a discourse. Studies on linguistic discourse analysis, however, generally tend to focus on a selection of constituents as they determine for example discourse actors, structures of conflicts, argumentation or characteristics of special types of texts. Subsequently, the thesis gives an overview of the characteristics of French [Footnote 2] approaches in discourse analysis as well as about some essential tendencies in this field in German Romance studies. In a next step, some French approaches are discussed and elements, categories, linguistic concepts as well as analytical steps are highlighted. The approaches that are taken into account in this part concern especially the analysis of discursive events as well as the polyphony and argumentation in discourse. Furthermore, it is shown that the linkage to an approach focussing on conflict structures from German studies is constitutive. In the ensuing part, the discursive components, the linguistic concepts as well as the methodological findings are merged into comprehensive analysis levels: (.)[Footnote 3] extra-discursive level, (I) prediscursive level, (II) scenography level, (III) subject level, (IV) perspective levels, (IV.1) agonal level, (IV.2) polyphonic level, (IV.3) argumentative level, (V) extensive level. Finally, these levels are exemplified in a detailed corpus-based linguistic analysis by using the example of security and surveillance. The corpora contain articles from various French newspapers and magazines as well as a radio online platform and some weblogs. It is organized in three time-related sections adapted to events relevant in the context of security and surveillance: (i) the revelations about the NSA spying scandal, (ii) the terrorist attacks on Charlie Hebdo in January 2015 and (iii) the multiple attacks on different bars, a stadium as well as the concert hall Bataclan in Paris in November 2015.[Footnote 1] This constellation is made possible by a binationally supervised doctoral project within the framework of a Cotutelle between the University of Heidelberg and the Université Paris-Est Créteil.[Footnote 2] The French language area is limited in this work to France as well as the French-speaking parts of Belgium and Switzerland.[Footnote 3] This is a level that is not linguistically motivated and is therefore excluded from the count.