Wave atoms and sparsity of oscillatory patterns

Abstract

We introduce "wave atoms" as a variant of 2D wavelet packets obeying the parabolic scaling wavelength ∼ (diameter)2. We prove that warped oscillatory functions, a toy model for texture, have a significantly sparser expansion in wave atoms than in other fixed standard representations like wavelets, Gabor atoms, or curvelets. We propose a novel algorithm for a tight frame of wave atoms with redundancy two, directly in the frequency plane, by the "wrapping" technique. We also propose variants of the basic transform for applications in image processing, including an orthonormal basis, and a shift-invariant tight frame with redundancy four. Sparsity and denoising experiments on both seismic and fingerprint images demonstrate the potential of the tool introduced. © 2007 Elsevier Inc. All rights reserved.