26 September 2013 Alpha molecules: curvelets, shearlets, ridgelets, and beyond
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The novel framework of parabolic molecules provides for the first time a unifying framework for (sparse) approximation properties of directional representation systems by, in particular, including curvelets and shearlets. However, the considered common bracket is parabolic scaling, which excludes systems such as ridgelets and wavelets. In this paper, we therefore provide a generalization of this framework, which we coin α-molecules, by introducing an additional parameter α, which specifies the extent of anisotropy in the scaling. We show that, for instance, both ridgelets and wavelets are in fact α-molecules. As an application of the concept, we then analyze the sparse approximation behavior of α-molecules. Utilizing the idea of sparsity equivalence, it is possible to identify large classes of α-molecules providing the same sparse approximation behavior.
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Philipp Grohs, Philipp Grohs, Sandra Keiper, Sandra Keiper, Gitta Kutyniok, Gitta Kutyniok, Martin Schäfer, Martin Schäfer, "Alpha molecules: curvelets, shearlets, ridgelets, and beyond", Proc. SPIE 8858, Wavelets and Sparsity XV, 885804 (26 September 2013); doi: 10.1117/12.2022665; https://doi.org/10.1117/12.2022665


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