To meet the limited bandwidth requirement of underwater acoustic channels,an efficient underwater video-coding scheme is presented,which is composed of preprocessing,intra-frame encoding,and inter-frame predictive encoding.A wavelet-based preprocessing method is used to effectively remove the visual redundancy of underwater images.According to the characteristics of underwater images,a wavelet tree-based wavelet difference reduction(WDR) algorithm is proposed to encode the intra-frame efficiently.Motion est...