Gabor representations present a number of interesting properties despite the fact that the basis functions are nonorthogonal and provide an overcomplete representation or a nonexact reconstruction. Overcompleteness involves an expansion of the number of coefficients in the transform domain and induces a redundancy that can be further reduced through computational costly iterative algorithms like Matching Pursuit. Here, a biologically plausible algorithm based on competitions between neighboring coefficients is employed for adaptively representing any source image by a selected subset of Gabor functions. This scheme involves a sharper edge localization and a significant reduction of the information redundancy, while, at the same time, the reconstruction quality is preserved. The method is characterized by its biological plausibility and promising results, but it still requires a more in depth theoretical analysis for completing its validation.

We present here a sparse coding algorithm dedicated exclusively to overcomplete Gabor wavelets and based on perceptual contour extraction methods. The algorithm has reduced computational cost and achieves compression rates similar to the standard image compression algorithms (JPEG and JPEG-2000) with the additional advantage of limiting the appearance of artifacts.