An improved zerotree wavelet image coder based on significance checking in wavelet trees

The Embedded Zerotree Wavelet (EZW) image compression algorithm has been widely used in real applications for its high compression performance. In this paper an improvement of EZW is presented. In the original EZW algorithm, when a new significant coefficient is generated, its children are all encoded, although its descendants maybe all insignificant, and thus its performance is affected. The improvement proposed in this paper is based on significance checking in wavelet trees (SCIWT). It is aimed to avoid encoding the children of each newly generated significant coefficient if it has no significant descendant. Experiments show that this proposed algorithm not only outperforms the original EZW over a wide range of compression ratios, but also completely retains all its key features without introducing any sophisticated and computationally complex method.