Design and analysis of medical images pyramid coding

In this paper, a new efficient technique for medical image compression is presented. It allows the ability of interactive picture transmission over low bandwidth channels, and achieves high compression ratio as well as good image fidelity. Within this paper, a method, which considers the intra-correlation properties, to design an optimal pyramids generation/synthesizing subsystem is first presented. By this, a pyramid structure which decomposes the input image waveforms into four pyramids is presented. In order to retain the important information for human eyes, we adopt different quantizer as well as coding algorithm for every pyramid according to human visual perceptual properties. Since the lower pyramids of most images are sparse and locally concentrated, i.e., many areas of the lower pyramids are inactive, a vector quantization accompanied with quadtree representation is used. As for the higher pyramids, signals are coded by simple variable length codewords algorithm. Since human eyes are more sensitive to low frequency changes, we apply finer quantizer to encode these pyramids. To generate the pyramids structure, a 2-D Quadrature Mirror Filter (2-D QMF) is used. Simulation results show that a reproduction of medical image with qualities be judged as faithful to the original image, can be obtained with SNR = 34.16 (dB) and bit rate 0.479 bpp.