基于小波变换的图像空间可分级压缩编码算法

Spatial Scalable Coding Algorithm of Images Based on Wavelet Transfor m

图像压缩算法如EZW和SPTHT都具有较高的压缩率,为了能使图像压缩编码算法同时具有较高的压缩率和良好的压缩性能,就SPIHT的算法进行分析,得出结论:随码率的增大,基础层所占的比率越来越低,同时,对包含边缘较多的图像。

Image compression algorithms such as EZW and SPIHT hav e a high compression rate. In order to have spatial scalability, SPIHT algorithm is analyzed in this paper. At the same compression rate, it is improved such th at it has spatial scalability. In the proposed algorithm, the coding information of a isolated pixel (significant or insignificant) is outputted to the bitstrea m which the pixel is located; the coding information of a set is outpu tted to the bitstream which according to the highest layer pixels of the set is located. Although the low-frequency subband is encoded together with the high-fr equency subbands, the experimental result show that the bit rate is very close t o the results of the low-frequency subband is encoded independently. Meanwhile, an optimal bit allocation scheme between base-layer bitstream and enhanced-layer bitstream is also given in this paper. The simulation results show that the rat io of base-layer bit rate to the total bit rate is different from images and the compression rate.