Virtual Super Resolution of Scale Invariant Textured Images Using Multifractal Stochastic Processes

International audienceWe present a new method of magnification for textured images featuring scale invariance properties. This work is originally motivated by an application to astronomical images. One goal is to propose a method to quantitatively predict statistical and visual properties of images taken by a forthcoming higher resolution telescope from older images at lower resolution. This is done by performing a virtual super resolution using a family of scale invariant stochastic processes, namely compound Poisson cascades, and fractional integration. The procedure preserves the visual aspect as well as the statistical properties of the initial image. An augmentation of information is performed by locally adding random small scale details below the initial pixel size. This extrapolation procedure yields a potentially infinite number of magnified versions of an image. It allows for large magnification factors (virtually infinite) and is physically conservative: zooming out to the initial resolution yields the initial image back. The (virtually) super resolved images can be used to predict the quality of future observations as well as to develop and test compression or denoising techniques

Domänen parallele Maschinen

A computational model is introduced, which abstracts and idealizes computers with access to fragment shaders. While the set of functions computable by this model remains the same, the running times can be drastically reduced through parallelization compared to conventional models. Some of the algorithms designed for the model can be approximated using fragment shaders. With an automatic transcompilation scheme, fragment shader programs can be generated automatically from a description in a high-level language.In dieser Arbeit wird ein Rechenmodell, das Computer mit Zugriff zu Fragment Shader abstrahiert und idealisiert, eingeführt. Zwar bleibt der Umfang der durch dieses Modell berechenbarer Funktionen gleich, jedoch können die Laufzeiten durch Parallelisierung im Vergleich zu herkömmlichen Modellen drastisch verkürzt werden. Einige der für das Modell entworfenen Algorithmen lassen sich mithilfe von Fragment Shadern approximieren. In einer Hochsprache beschriebene Algorithmen werden automatisiert in Fragment Shader Programme übersetzt

On the Geometry of IFS Fractals and its Applications

Visually complex objects with infinitesimally fine features, naturally call for mathematical representations. The geometrical property of self-similarity - the whole similar to its parts - when iterated to infinity generates such features. Finite sets of affine contractions called Iterated Function Systems (IFS), with their compact attractors IFS fractals, can be applied to represent detailed self-similar shapes, such as trees or mountains. The fine local features of such attractors prevent their straightforward geometrical handling, and often imply a non-integer Hausdorff dimension. The main goal of the thesis is to develop an alternative approach to the geometry of IFS fractals in the classical sense via bounding sets. The results are obtained with the objective of practical applicability. The thesis thus revolves around the central problem of determining bounding sets to IFS fractals - and the convex hull in particular - emphasizing the fundamental role of such sets in their geometry. This emphasis is supported throughout the thesis, from real-life and theoretical applications to numerical algorithms crucially dependent on bounding

Mutable Objects, Spatial Manipulation and Performance Optimization

Contemporary digital design techniques are powerful, but disjoint. There are myriad emerging ways of manipulating design components, and generating both functional forms and formal functions. With the combination of selective agglomeration, sequencing, and heuristics, it is possible to use these techniques to focus on optimizing performance criteria, and selecting for defined characteristics. With these techniques, complex, performance oriented systems can emerge, with minimal input and high effectiveness and e""ciency. These processes depend on iterative loops for stability and directionality, and are the basis for optimization and refinement. They begin to approach cybernetic principles of self-organization and equilibrium. By rapidly looping this process, design ‘attractors’– shared solution components–become visible and accessible. In the past, we have been dedicated to selecting the contents of the design space. With these tools, we can now ask, what are the inputs to the design process, what is the continuum or spectrum of design inputs, and what are the selection criteria for the success of a design-aspect? These new questions allow for a greater coherence within a particular cognitive model for the designed and desired object. There are ways of using optimization criteria that enable design freedom within these boundaries, while enforcing constraints and maintaining consistency for selected processes and product aspects. The identification and codification of new rules for the process support both flexibility and the potential for cognitive restructuring of the process and sequences of design

Digital Image Processing

Newspapers and the popular scientific press today publish many examples of highly impressive images. These images range, for example, from those showing regions of star birth in the distant Universe to the extent of the stratospheric ozone depletion over Antarctica in springtime, and to those regions of the human brain affected by Alzheimer’s disease. Processed digitally to generate spectacular images, often in false colour, they all make an immediate and deep impact on the viewer’s imagination and understanding. Professor Jonathan Blackledge’s erudite but very useful new treatise Digital Image Processing: Mathematical and Computational Methods explains both the underlying theory and the techniques used to produce such images in considerable detail. It also provides many valuable example problems - and their solutions - so that the reader can test his/her grasp of the physical, mathematical and numerical aspects of the particular topics and methods discussed. As such, this magnum opus complements the author’s earlier work Digital Signal Processing. Both books are a wonderful resource for students who wish to make their careers in this fascinating and rapidly developing field which has an ever increasing number of areas of application. The strengths of this large book lie in: • excellent explanatory introduction to the subject; • thorough treatment of the theoretical foundations, dealing with both electromagnetic and acoustic wave scattering and allied techniques; • comprehensive discussion of all the basic principles, the mathematical transforms (e.g. the Fourier and Radon transforms), their interrelationships and, in particular, Born scattering theory and its application to imaging systems modelling; discussion in detail - including the assumptions and limitations - of optical imaging, seismic imaging, medical imaging (using ultrasound), X-ray computer aided tomography, tomography when the wavelength of the probing radiation is of the same order as the dimensions of the scatterer, Synthetic Aperture Radar (airborne or spaceborne), digital watermarking and holography; detail devoted to the methods of implementation of the analytical schemes in various case studies and also as numerical packages (especially in C/C++); • coverage of deconvolution, de-blurring (or sharpening) an image, maximum entropy techniques, Bayesian estimators, techniques for enhancing the dynamic range of an image, methods of filtering images and techniques for noise reduction; • discussion of thresholding, techniques for detecting edges in an image and for contrast stretching, stochastic scattering (random walk models) and models for characterizing an image statistically; • investigation of fractal images, fractal dimension segmentation, image texture, the coding and storing of large quantities of data, and image compression such as JPEG; • valuable summary of the important results obtained in each Chapter given at its end; • suggestions for further reading at the end of each Chapter. I warmly commend this text to all readers, and trust that they will find it to be invaluable. Professor Michael J Rycroft Visiting Professor at the International Space University, Strasbourg, France, and at Cranfield University, England

Réseaux ad hoc : système d'adressage et méthodes d'accessibilité aux données

RÉSUMÉ Au cours de la dernière décennie, un nouveau type de réseaux sans fil a suscité un grand intérêt dans la communauté scientifique: ce sont les réseaux ad hoc. Ils existent sous la variante des réseaux mobiles ad hoc (MANET), et des réseaux de capteurs sans fil (RCSF). Les réseaux mobiles ad hoc sont constitués de noeuds mobiles qui communiquent les uns avec les autres sans l‘aide d‘une d'infrastructure centralisée. Les noeuds se déplacent librement et sont soumis à des déconnexions fréquentes en raison de l'instabilité des liens. Cela a pour conséquence de diminuer l'accessibilité aux données, et de modifier la façon dont les données sont partagées dans le réseau. Comparable aux réseaux MANET, un RCSF est composé d'un ensemble d'unités de traitements embarquées, appelées capteurs, communiquant via des liens sans fil et dont la fonction principale est la collecte de paramètres relatifs à l'environnement qui les entoure, telles que la température, la pression, ou la présence d'objets. Les RCSF diffèrent des MANET de par le déploiement à grande échelle des noeuds, et trouvent leur application dans diverses activités de la société, tels les processus industriels, les applications militaires de surveillance, l'observation et le suivi d'habitat, etc. Lorsqu‘un grand nombre de capteurs sont déployés avec des dispositifs d'actionnement appelés acteurs, le RCSF devient un réseau de capteurs et d‘acteurs sans fil (RCASF). Dans une telle situation, les capteurs collaborent pour la détection des phénomènes physiques et rapportent les données afférentes aux acteurs qui les traitent et initient les actions appropriées. De nombreux travaux dans les RCSF supposent l'existence d'adresses et d'infrastructures de routage pour valider leurs propositions. Cependant, l‘allocation d‘adresses et le routage des données liées aux événements détectés dans ces réseaux restent des défis entiers, en particulier à cause du nombre élevé de capteurs et des ressources limitées dont ils disposent. Dans cette thèse, nous abordons le problème de l'accessibilité aux données dans les MANET, et les mécanismes d‘adressage et de routage dans les RCSF de grande taille.----------ABSTRACT During the last decade, a new type of wireless networks has stirred up great interest within the scientific community: there are ad hoc networks. They exist as mobile ad hoc networks (MANET), and wireless sensor (WSN). The mobile ad hoc networks consist of mobile nodes that communicate with each other without using a centralized infrastructure. The nodes move freely and are subject to frequent disconnections due to links instability. This has the effect of reducing data accessibility, and change the way data are shared across the network. Similar MANET networks, a WSN consists of a set of embedded processing units called sensors that communicate with each other via wireless links. Their main function is the collection of parameters relating to the environment around them, such as temperature, pressure, motion, video, etc. WSNs differ from the MANETs due to the large scale deployment of nodes, and are expected to have many applications in various fields, such as industrial processes, military surveillance, observation and monitoring of habitat, etc. When a large number of sensors which are resource-impoverished nodes are deployed with powerful actuation devices, the WSN becomes a Wireless Sensor and Actor Network (WSAN). In such a situation, the collaborative operation of sensors enables the distributed sensing of a physical phenomenon, while actors collect and process sensor data to perform appropriate action. Numerous works in WSN assumes the existence of addresses and routing infrastructure to validate their proposals. However, assigning addresses and delivering detected events remains highly challenging, specifically due to the sheer number of nodes. In this thesis, we address the problem of data accessibility in MANET, and that of addressing and routing in large scale WSN. This involves techniques such as data caching and replication to prevent the deterioration of data accessibility. The addressing system in WSN includes a distributed address allocation scheme and a routing infrastructure for both actors and sensors. Moreover, with the birth of the multimedia sensors, the traffic may be mixed with time sensitive packets and reliability-demanding packets. For that purpose, we also address the problem of providing quality of service (QoS) in the routing infrastructure for WSN

Building networks of Markov decision processes to achieve synchronised behaviour from complex multi-agent systems

Complex multi-agent systems, consisting of multiple decision making agents as part of a larger collective, are particularly complex control problems, because of the potential for emergent (and potentially undesirable or even unsafe) behaviours to arise from the interaction between separate agents. When a number of autonomous systems interact with one another, be they robotic systems, intelligent software agents, or autonomous vehicles, they can become a complex multi-agent system, potentially prone to emergent behaviours. Understanding, controlling and assuring complex multi-agent systems is a difficult challenge for the systems engineer, through all stages of the engineering lifecycle. There is often no simple mechanism to control the behaviour of the whole, and no established formal techniques for system proving. The underpinning mathematics is too far removed from the systems of years gone by for established techniques to be transferrable. This thesis takes a fresh look at this topic using the mathematical framework of complexity science and theoretical aspects of systems science to begin to tackle this knotty problem domain. Synchronised robotics is a concept introduced for this PhD to describe systems consisting of multiple robotic appendages acting independently based on simple control logic, but unbeknownst to the individual robots also acting as part of a carefully choreographed collective system. Synchronised robotics provides an ideal application area from which to develop and explore an exemplar scenario. Production line robotics are the chosen exemplar. This thesis shows how systems science principles can be utilised to represent all kinds of complex multi-agent system, with different internal network structures between decision nodes mirroring the myriad of ways that a systems architect might choose to construct his or her system. It then proceeds to show how to generalise the Markov Decision Process (MDP) formulation to these networks, to produce models of interactive autonomy. This novel approach to systems design and proving is brought to life through application to the production line robotics exemplar, for which a mathematical model based on the processes and techniques described has been built, tested, and initial results obtained demonstrating the potential efficacy of the approach for capturing the complex behaviours displayed, providing a control mechanism with improved resilience to correcting undesirable emergent behaviours, and pointing a way towards a potential future system proving tool for multi-agent systems

Complexity, Emergent Systems and Complex Biological Systems:\ud Complex Systems Theory and Biodynamics. [Edited book by I.C. Baianu, with listed contributors (2011)]

An overview is presented of System dynamics, the study of the behaviour of complex systems, Dynamical system in mathematics Dynamic programming in computer science and control theory, Complex systems biology, Neurodynamics and Psychodynamics.\u