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The Project SMALL

Main goal

The main goal of the project is to develop a new foundational framework for processing signals, using adaptive sparse structured representations.

The project SMALL involves 5 partners and is structured towards 6 objectives.


arrow_bullet While sparsity provides an enormous dimensionality reduction, it does not fully capture all the structure of natural data that is readily available to us. For example, in images, the size of wavelet coefficients decays down the wavelet tree and there are strong dependencies between coefficients due to the underlying geometry of images.

arrow_bullet Suitable sparse models have yet to be discovered for many "exotic" or heterogeneous types of data such as multi-channel or multi-modal data, as found in audiovisual (typically two sound tracks and a video track), bio-medical, or climate monitoring applications.

 arrow_bulletTraditionally, the idea of using learned dictionaries implies computational cost. This is because the complexity issue is left aside at the learning stage. To deploy learned dictionaries on large-scale data, learning algorithms should encompass this aspect.

arrow_bullet The state-of-the-art in dictionary learning assumes fully unstructured dictionaries.
Instead, we believe dictionaries should reflect the natural structures present in signals, such as shift-invariance, rotation-invariance, and/or scale-invariance.

arrow_bullet The dictionary design problem has been essentially addressed through empirical
algorithms. This is in contrast to the extensive body of theoretical work providing solid foundations to sparse decomposition algorithms, and calls for a solid theoretical underpinning of dictionary design algorithms.





Rémi Gribonval, coordinator
Equipe-Projet METISS
INRIA Rennes - Bretagne Atlantique
Campus de Beaulieu
F-35042 Rennes cedex, France.

Phone: (+33/0) 299 842 506
Fax: (+33/0) 299 847 171
E-MAIL: contact