Projection-based spatially adaptive reconstruction of block transform compressed images

In conventional block-transform coding, the compressed images are decoded using only the transmitted transform data. In this paper, we formulate image decoding as an image recovery problem. According to this approach, the decoded image is reconstructed using not only the transmitted data, but in addition, the prior knowledge that images before compression do not display blocking artifacts. A spatially-adaptive image recovery algorithm is proposed based on the theory of projections onto convex sets. Numerical experiments demonstrate that the proposed algorithm yields images superior to those from both the JPEG deblocking recommendation and a projection-based image decoding approach.