A wavelet zerotree image coding method based on memory optimization and heuristic Depth Finding Strategy (DFS) is presented in this paper.The form of flag and heuristic DFS are introduced in the sorting and refining process.The flag map instead of lists in the refining process is used to keep significant wavelet coefficients.The DFS is used to search insignificant wavelet sets in the sorting process.Therefore

both the memory of coding and the oriented information of sorting are decreased.Experimental results show that compared to the existing wavelet zerotree coding method

the memory is significantly reduced.Although the PSNR is little lower than SPIHT's

it is higher than EZW's and LZC's.This proposed method provides an efficient hardware implementation.