Sparse Representation in Structured Dictionaries With Application to Synthetic Aperture Radar

Sparse signal representations and approximations from overcomplete dictionaries have become an invaluable tool recently. In this paper, we develop a new, heuristic, graph-structured, sparse signal representation algorithm for overcomplete dictionaries that can be decomposed into subdictionaries and whose dictionary elements can be arranged in a hierarchy. Around this algorithm, we construct a methodology for advanced image formation in wide-angle synthetic aperture radar (SAR), defining an approach for joint anisotropy characterization and image formation. Additionally, we develop a coordinate descent method for jointly optimizing a parameterized dictionary and recovering a sparse representation using that dictionary. The motivation is to characterize a phenomenon in wide-angle SAR that has not been given much attention before: migratory scattering centers, i.e., scatterers whose apparent spatial location depends on aspect angle. Finally, we address the topic of recovering solutions th...

• Type: Journal
• Year: 2008
• Where: TSP
• Authors: Kush R. Varshney, Müjdat Çetin, John W. Fisher III, Alan S. Willsky
• Keywords: Image Formation, Overcomplete Dictionaries, Sparse Signal, TSP 2008