Rounding transform based approach for lossless subband coding

In this paper, a new approach is proposed, the rounding transform (RT) based lossless subband coding. For the such purpose, an extended version of RT, namely overlapping RT (ORT), is defined in the Z-transform domain and used to develop the lossless subband coding system. The main idea is that the polyphase matrix of the analysis filter bank is decomposed into several ORT matrices of size 2 by 2. Compared to the previous scheme (the lifting), the proposed scheme gives not only simpler mathematical representation, but also allows various possibilities when a given filter bank is implemented. As examples, five filter banks are applied to lossless image compression by the proposed ORT and their performances are compared in terms of the total lossless first order entropy.