图像经过矢量量化后得到的索引图具有很强的统计相关性,从而使得邻近块的索引以较大的概率相等或偏移量较小。按照某种准则对码书进行排序,可以有效增强索引之间的相关性。基于平方欧几里得距离提出一种新的码书按距离排序方法。与传统的按均值、方差和能量等排序方法相比,距离排序能大大提高索引图的相关性,使索引之间的偏移量向值小的方向明显集中。将距离排序后的码书用于AICS(adaptive index coding scheme)算法,实现了更好的压缩性能。

The index map after vector quantization has a strong statistical correlation.That means the neighboring indices are the same or the offset between them is very small.Codebook sorting can,according to some criteria,enhance the correlation among neighboring indices.Based on the squared Euclidean distance between code words,a new codebook sorting method is proposed.Compared with the conventional mean-ordered codebook,the distance-ordered codebook has a much higher correlations between neighboring indices and the offset become even smaller.As a result,distance-ordered codebook can also significantly improve the compression efficiency of the AICS (adaptive index coding scheme) algorithm.