JPEG2000码率控制算法的改进

Modifying the rate control algorithm of JPEG2000

针对在低码率时,JPEG2000编码中存在大量计算冗余,提出一种快速有效算法,该算法通过查表法快速估计斜率值并找到最佳截断点,这样不仅避免了斜率值的浮点除法运算,而且在低码率时,大量码块编码过程被丢弃,因此使EBCOT中层1编码的计算量大大减少。实验结果表明,该算法比PCRD算法的编码时间及存储器开销都大幅度下降,而重构图像质量相当。

At low bit rate, most computation in Tier - 1 of JPEG2000 is redundant. A fast and efficient rate control approach for JPEG2000 is proposed. The proposed approach can estimate the slop value quickly through a simple looking up table and find out optimal truncation point. So calculating the slop value in man- ner of the floating - point division does not need, The computation is reduced greatly because of a large of unnecessary ceding operations of Tier - 1 are skipped at low hit rate. The experiments show that the encoding time and memory usage can be reduced greatly, while the reconstructed image quality is nearly same as PCRD in JPEG2000 standard.