Concurrent encoding in hierarchical trees for wavelet based image compression

Wavelet based compression approaches becomes very popular in the last few years. In this paper, a method called CEIHT (concurrent encoding in hierarchical trees) rooted from SPIHT is proposed. This method tries to explore the relationship between adjacent resolution levels and encodes multiple coefficients with three fixed Huffman tables at the same time. Consistent coding efficiency improvement is achieved compared to the original SPIHT. Though wavelet based compression methods usually encode on a whole image, block based approaches have to be applied in many low-cost embedded applications because their memory space and computation power are usually limited. The proposed method is especially efficient in such cases. The performance of the proposed method is compared favorably to the highly acclaimed EBCOT based J2K when small coding block sizes are necessary.