Séminaire Performance et Généricité

From LRDE


À propos du séminaire

La modélisation orientée objet permet la classification des problèmes de calcul scientifique, et par conséquent, par la factorisation qu'elle rend possible, elle fournit un excellent support pour la fédération d'efforts de développement. Malheureusement les performances en pâtissent souvent. De nouveaux langages, de nouvelles techniques de programmation réconcilient performance et généricité, permettant la naissance de bibliothèques de nouvelle génération (Boost, Olena, Vcsn, etc.).

L'objet de ce séminaire est la diffusion du savoir et des compétences sur la modélisation de bibliothèques métiers génériques et performantes.

Mots clés: Calcul Scientifique, Distribution, Génie Logiciel, Généricité, Grille, Langages, Multi-cœur, Paradigmes de Programmation, Parallélisme, Recherche reproductible.

Comment venir: Contact.

Prochaines séances

Vendredi 14 décembre 2018, 11h-12h, Amphi IP12A

Toward myocardium perfusion from X-ray CT

Clara Jaquet (ESIEE Marne-la-Vallée)

Recent advances in medical image computing have resulted in automated systems that closely assist physicians in patient therapy. Computational and personalized patient models benefit diagnosis, prognosis and treatment planning, with a decreased risk for the patient, as well as potentially lower cost. HeartFlow Inc. is a successful example of a company providing such a service in the cardiovascular context. Based on patient-specific vascular model extracted from X-ray CT images, they identify functionally significant disease in large coronary arteries. Their combined anatomical and functional analysis is nonetheless limited by the image resolution. At the downstream scale, a functional exam called Myocardium Perfusion Imaging (MPI) highlights myocardium regions with blood flow deficit. However, MPI does not functionally relate perfusion to the upstream coronary disease. The goal of our project is to build the functional bridge between coronary and myocardium. To this aim we propose an anatomical and functional extrapolation. We produce an innovative vascular network generation method extending the coronary model down to the microvasculature. In the resulting vascular model, we compute a functional analysis pipeline to simulate flow from large coronaries to the myocardium, and to enable comparison with MPI ground-truth data.

After completing a technological university degree in biology at Creteil, Clara Jaquet obtained the diploma of biomedical engineer from ISBS (Bio-Sciences Institute) in 2015. She worked for one year at HeartFlow Inc, California, before starting a PhD at ESIEE, Université Paris-Est, within the LIGM laboratory, on a research project jointly with the same company.




Archives

Mercredi 4 juillet 2018, 11h-12h, Amphi IP11

Y a-t-il une théorie de la détection des anomalies dans les images digitales?

Jean-Michel Morel (École Normale Supérieure Paris-Saclay)

Dans ce travail en collaboration avec Axel Davy, Mauricio Delbracio et Thibaud Ehret, je passerai en revue les classes d'algorithmes dont le but est de détecter des anomalies dans les images digitales. Ces détecteurs répondent au difficile problème de trouver automatiquement des exceptions dans des images de fond, qui peuvent être aussi diverses qu'un tissu ou une mammographie. Des méthodes de détection ont été proposées par milliers car chaque problème nécessite un modèle de fond différent. En analysant les approches existantes, nous montrerons que le problème peut être réduit à la détection d'anomalies dans les images résiduelles (extraites de l'image cible) dans lesquelles prédominent le bruit et les anomalies. Ainsi, le problème général et impossible de la modélisation d'un fond arbitraire est remplacé par celui de modèliser un bruit. Or un modèle de bruit permet le calcul de seuils de détection rigoureux. L'approche au problème peut donc être non supervisée et fonctionner sur des images arbitraires. Nous illustrerons l'usage de la théorie de détection dite a contrario, qui évite la sur-détection en fixant des seuils de détection prenant en compte la multiplicité des tests.

Mathématicien de formation, docteur de l'Université Pierre et Marie Curie, Assistant à Marseille-Luminy, maître de conférences et professeur à l'Université Paris-Dauphine puis à l'ENS Cachan, JMM a fait ses premiers travaux sur les équations aux dérivées partielles non-linéaires et les méthodes variationnelles. Il s'est ensuite consacré au développement d'outils mathématiques pour le traitement et l'analyse d'images et la modélisation de la perception visuelle.

https://sites.google.com/site/jeanmichelmorelcmlaenscachan/



Mercredi 13 juin 2018, 11h-12h, Amphi 401

Hierarchical image representations: construction, evaluation and examples of use for image analysis

Camille Kurtz (LIPADE, Université Paris Descartes)

Hierarchical image representations have become increasingly popular in image processing and computer vision over the past decades. Indeed, they allow a modeling of image contents at different (and complementary) levels of scales, resolutions and semantics. Methods based on such image representations have been able to tackle various complex challenges such as multi-scale image segmentation, image filtering, object detection, recognition, and more recently image characterization and understanding. In this talk, we will focus on the binary partition tree (BPT), which is a well-known hierarchical data-structure, frequently involved in the design of image segmentation strategies. In a first part, we will focus on the construction of such trees by providing a generalization of the BPT construction framework to allow one to embed multiple features, which enables handling many metrics and/or many images. In a second part, we will discuss how it may be possible to evaluate the quality of such a structure and its ability to reconstruct regions of the image corresponding to segments of reference given by a user. Finally, we will see some examples of image analysis and recognition processes involving these hierarchical structures. The main thematic application is remote sensing and satellite image analysis.

Camille Kurtz obtained the MSc and PhD from Université de Strasbourg, France, in 2009 and 2012. He was a post-doctoral fellow at Stanford University, CA, USA, between 2012 and 2013. He is now an Associate Professor at Université Paris Descartes, France. His scientific interests include image analysis, data mining, medical imaging and remote sensing.

www.math-info.univ-paris5.fr/~ckurtz/



Mercredi 30 mai 2018, 11h-12h, Amphi IP11

Partial but Precise Loop Summarization and Its Applications

Jan Strejcek, Masaryk University

We show a symbolic-execution-based algorithm computing the precise effect of a program cycle on program variables. For a program variable, the algorithm produces an expression representing the variable value after the number of cycle iterations specified by parameters of the expression. The algorithm is partial in the sense that it can fail to find such an expression for some program variables (for example, it fails in cases where the variable value depends on the order of paths in the cycle taken during iterations).

We present two applications of this loop summarization procedure. The first is the construction of a nontrivial necessary condition on program input to reach a given program location. The second application is a loop bound detection algorithm, which produces tighter loop bounds than other approaches.

Jan Strejcek is an associate professor at the Faculty of Informatics of Masaryk University located in Brno, Czech Republic. He received his PhD in Computer Science (2005) and Master degrees in Mathematics (2000) and Computer Science (2001) from the same university. His current research focuses on automata over infinite words, automatic program analysis, and SMT-solving of quantified bitvector formulae.

https://www.fi.muni.cz/~xstrejc/



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