An approach to subband dct image coding

For transform image coding, we sometimes need to make tradeoffs among subimage size, computational effort, and coding efficiency in order to obtain good overall performance. Though a smaller size subimage is efficient for computation, it introduces blocking effect. This paper proposes an algorithm to compute a large size DCT through small size transforms by making use of the subband decomposition technique. Based on this algorithm, an efficient coding approach is proposed to simulate a full-size DCT image coding. Compared with the conventional DCT transform coding, this coding technique has the advantages of (i) no blocking effect, (ii) higher quality reconstructed images, and (iii) less computational effort required.