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Showing papers on "Contourlet published in 1996"


Journal ArticleDOI
TL;DR: The Laplacian pyramid is appropriate for lossy image compression; conversely, the reduced-difference pyramid (RDP), having as many data as pixels, gives a better performance with lossless encoding.
Abstract: The Laplacian pyramid (LP) is appropriate for lossy image compression; conversely, the reduced-difference pyramid (RDP), having as many data as pixels, gives a better performance with lossless encoding. A reduced LP is designed by discarding the anti-aliasing filter and adopting a half-band interpolator, thus retaining three over four of the LP coefficients. Lossless coding outperforms both LP and RDP, especially when dealing with medical images.

60 citations


Journal ArticleDOI
TL;DR: This work introduces a Gaussian pyramid wavelet transform for multiresolution analysis of images, and shows that with a slight modification of the original Gaussian Pyramid a decomposition algorithm is yielded, which hasGaussian pyramid reduce and expand operations with a perfect reconstruction property.

58 citations


Proceedings ArticleDOI
07 May 1996
TL;DR: A combined multiresolution/multi-orientation representation by directional wavelet transform (DWT) is introduced in this paper and is applied successfully to feature enhancement and extraction of X-ray mammographic images.
Abstract: Multi-resolution and multi-orientation are part of the biological mechanism of human visual system. The interest in multi-resolution image analysis has been growing rapidly. Comparatively, however, the multi-orientation method has received less attention. Based on the relationship between multifrequency channel decomposition and the wavelet model developed by Mallat [1989], a combined multiresolution/multi-orientation representation by directional wavelet transform (DWT) is introduced in this paper. Because of its high orientation selectivity, the DWT allows the processing of directional information more efficiently. It is applied successfully to feature enhancement and extraction of X-ray mammographic images.

30 citations