DCT Quantization - Entropy Coding Decoding Entropy Channel Two Level Inverse Two Level Quantization IDCT

Motivated by Shapiro's embedded zerotree wavelet coding (EZW) and Taubman and Zakhor's layered zero coding (LZC), we propose a layered DCT image compression scheme, which generates an embedded bit stream for DCT coeecients according to their importance. The new method allows progressive image transmission and simpliies the rate-control problem. In addition to these functionalities, it provides a substantial rate-distortion improvement over the JPEG standard when the bit rates become low. For example, we observe a bit rate reduction with respect to the JPEG Huuman and arithmetic coders by about 60% and 20%, respectively, for a bit rate around 0.1bpp.