Adaptive denoising and lossy compression of images in transform domain

A new algorithm for removing mixed noise from images based on combining an impulse removal operation with local adaptive filtering in transform domain is proposed in this paper. The key point is that the operation is designed so that it removes impulses while maintaining as much as possible of the f requency content of the original image. The second stage is an adaptive den oising operation based on local transform. The proposed algorithm works wel l in denoising images corrupted by a white (Gaussian, Laplacian, exponentia l) noise, impulsive noise, and their mixtures. Comparison of the new algori thm with known techniques for removing mixed noise from images shows the ad vantages of the new approach, both quantitatively and visually. In this pap er we also apply transform-based denoising methods for removing blocking an d ringing artifacts from decompressed block transform or wavelet coded imag es. The method is universal and applies to any compression method used (C) 1999 SPIE and IS&T. [S1017-9909(99)00803-X].