Embedded Descendent-Only Zerotree Wavelet Coding for Image Compression

The Embedded Zerotree Wavelet (EZW) coder which can be considered as a degree-0 zerotree coder, and Set Partitioning In Hierarchical Trees (SPIHT) coder which can be considered as a degree-2 zerotree coder are two well-known image compression techniques. However, the performance of a degree-1 zerotree coder has not been well investigated. In this paper, an Embedded Descendent-Only Zerotree Wavelet (EDOZW) coder which can he considered as a degree-1 zerotree coder is proposed. The EDOZW coder is a modified version of SPIRT coder with Arithmetic Coding (SPIHT-AC). When coding the entry in the List of Insignificant Set (LIS) in SPIHT, it is necessary to first determine whether the entry is Type A or Type B. Then, a different scheme is used to handle the entry. But in contrast to SPIHT, it is no longer necessary to differentiate the type of entry in EDOZW. Only one type of entry is used in EDOZW and a recursive algorithm can be used to encode all the entries easily. This will help to reduce the overall complexity. Moreover, the EDOZW also achieved better performance at high bit rates. The EDOZW can serve as an alternative solution for image compression other than EZW and SPIHT.