wavelet transform is adopted to decompose an image into a group of multiresolution sub-images.An improved coding scheme is developed which have considered the gray distribution properties of sub-image and human being's vision.image data have been reduced farther by using dual-pyramid data structure for sub-image coding.which have great similarity with each other.The mean compression rate and signal-to-noise ratio for 10 cow's image is 26.2 and 30.6.respectively.The reconstructural quality of image is high.