一种有效的JPEG2000压缩率控制算法

JPEG2000是一种新型的图像编码标准,它具有优于JPEG标准的率-失真性能.但JPEG2000标准的压缩后率失真(PCRD)优化算法效率较低,尤其在低比特率时JPEG2000编码的熵编码部分(EBCOTTier-1)将有很大一部分计算浪费,因为许多经过编码的比特流在经过JPEG2000压缩码率控制算法后被截断丢弃.提出一种有效的压缩码率控制算法,它利用率-失真斜率的两个属性得到优化的截断点,不需要所有的编码过程,并给出了整个处理过程.与JPEG2000原有的PCRD算法相比,所提出算法可以快速搜索到优化截断点并可减少存储空间尺寸,还可获得与PCRD算法几乎相同的图像质量.

An Efficient Rate Control Scheme for JPEG2000

JPEG2000 is a new image coding standard which can provide better rate-distortion performance than the JPEG standard.But the post-compression rate-distortion(PCRD)optimization scheme in JPEG2000 is inefficient.Most of the computation in the entropy coder(EBCOT Tier-1)of JPEG2000 is a waste especially at lower bit-rate.That is because many coded bit-stream will be truncated after the rate control method of JPEG2000.An efficient scheme for JPEG2000 rate control is proposed.This scheme utilizes the two properties of the rate-distortion slope to achieve the optimized truncation points and also the whole processing steps of the rate control scheme is given.Compared with the standard PCRD algorithm,the proposed algorithm can quickly searching for the optimum truncation points and not require encoding all the coding passes.Using this scheme,the computation complexity and the memory size will be greatly reduced.Moreover,the proposed scheme can achieve the same image quality as the PCRD algorithm used by JPEG2000 now.