A novel hierarchical coding algorithm based on multi-subsample and the all phase IDCT interpolation

This paper proposes a novel hierarchical coding algorithm based on the All Phase IDCT (APIDCT) interpolation. The All Phase Digital Filter (APDF) is a new type of linear phase filter. For a data vector with a length of N obtained by blocking a signal, there are N different phase data blocks that include the same sampling point. Through taking the mean of the N values as the filtering output, the APDF can eliminate different meanings of the orthogonal transform filtering values of those data vectors and thereby the block effect. According to this idea, this paper deduces the formula of two-dimension APIDCT. Then, this paper compares the performances of several kinds of APDF and demonstrates that the APIDCT filter has the best performance in image interpolation. By combining the interpolation with multi-subsampling and adaptive arithmetic coding, a simple hierarchical image-coding algorithm is shaped up. Ibis technique can be used to scalable coding in spatial resolution. The simulation results show that the compression ratio and restored image quality better than JPEG compression can be achieved by only three layers, and no block effect has been found even in high compression ratio.