Study Of Accurate Rate Control For JPEG2000

JPEG2000 uses digital wavelet transformation (DWT) in which the energy response more centralized, and D.Taubman proposed embedded block coding with optimized truncation (EBCOT) algorithm based on rate distorted optimization truncation to take its core algorithm, and uses the bit-plane entropy encoder, finally organizes the embedded code block stream in different layers to obtain the most advanced compressibility. It is an extremely important characteristic for JPEG2000 to realize Progressive Transmission (evolution transmission). The JPEG2000 expandable transmission is decided to a great extent by the compression rate control algorithm, JPEG2000 standard suggested PCRD (Post - compression Rate Distortion Optimization) algorithm which can reach the best compression quality under certain image compression storage space. But when the accurate control of output code rate is required, accurate target code length must be provided for code stream truncation. But there also contains some header information in the output stream, thus when rate distorted optimization truncation is processed, the code length of these information must be considered either. If the code length of these information is ignored in the truncation process, a much bigger output code rate will be obtained by directly using the target length which obtains with the input rate. Based on the above consideration, this paper proposed an algorithm by reserving the packet header length in the rate distorted optimization truncation process, and unifies the method of rejecting the smallest length-distortion slope point. the experimental result indicates that this algorithm can achieve an accurate rate control without reducing the quality of the compressed image.