革新知能統合研究センター

Speaker: Prof. Yannick Berthoumieu (Université de Bordeaux, France)

Title: Beyond Euclidean Fisher Vectors for Coding Feature Spaces

Abstract:
Recently, specific works have shown that exploiting the geometry of non-Euclidean space for some parametric families makes it possible to improve performance of the estimation or classification algorithms well known in the Euclidean case. In this presentation, we consider the space of structured descriptors such as covariance matrices to characterize signals or images (spatial or temporal dependencies, correlation between descriptors, …). In this context, we propose to formalize the concept of Riemannian Gaussian probability laws, which corresponds in practice to consider an i.i.d population of the empirical covariance matrices characterized by a covariance “mean” and a “scalar dispersion” parameter describing the centered variability of the covariance set. Second, from Riemannian Gaussian law, the extension to the case of the mixing models is considered. This extension makes it possible to define the generalization of Fisher vectors to the context of the structured descriptors for classification task. From this paradigm of geometric inference problem, we illustrate our point of view from different classification tasks, i.e. textured images, motion analysis and EEG analysis for BCIs (Brain Computer Interface).

Bio:
Yannick Berthoumieu received his Ph.D. degree in Electrical Engineering in 1996. He joined the Bordeaux Institute of Technology, France, in 1997 as an assistant professor. Since 2007 he is a full Professor of the Bordeaux Institute of Technology, where he currently heads the Signal and Image Processing Group (GSI) belonging to the CNRS IMS Laboratory.
His research activities covers areas such as statistical image and video processing, information geometry, as well as probabilistic manifolds in machine learning, classification, segmentation, superresolution and inversion algorithms focused on textural content for optical, radar and hyperspectral imaging applications. The Group he manages carries long terms joint partnerships with Total Company, Thales Aircraft Group, the CEA, i.e. the French Alternative Energies Authority of Atomic Energy.
Prof. Berthoumieu co-organized international Conferences and Workshops including the IEEE ICIP, IEEE CAMSAP, and the IEEE SSP. He was the General Chair of the IEEE IVMSP Workshop (2016), and General Chair of the GRETSI conference (2011) both organized in Bordeaux. He is served as area chair for conferences such as EUSIPCO, ICIP or conference on Geometric Science of Information. Since 2016, he joined the IEEE technical committee.