Subspaces of Quantization Artifacts for Image Transform Compression

This paper presents a new algorithm for reducing quantization artifacts in transform coded images. For transform coded signals, we analytically show that one can determine linear subspaces where most of the quantization artifacts reside. We formulate statistical constraints that identify these subspaces and propose a simple algorithm that removes them. Our formulation is general and is not tied to a specific linear transform or quantizer. The proposed algorithm, which is non-iterative, non-redundant and computationally inexpensive, results in visually pleasing images and competitive PSNR values when compared to the best post-processing results reported in the literature.