由于通过RS统计分析和Chi—square统计分析，可以察觉以LSB方法密写的秘密信息的存在，因此为提高密写方案的安全性，提出了一种改进的LSB密写方案，即如果被嵌入的秘密比特与原始灰度的最低位相同，便不作改动；否则根据周围像素作增1或减1的调整，而在接收方，只需将载体图象的最低位取出即可恢复秘密信息．大量图象的模拟实验结果说明，该方案不仅可以抵抗RS分析和Chi—square分析，而且不增加失真度．并可保持计算量小、提取方便的优点．并表明改进方案对抵抗这两种密写分析是有效的．

RS and Chi-square analyses are powerful steganalytic techniques for detecting the presence of secret information embedded in the least-significant-bit(LSB) plane of digital images. This paper describes an improved LSB steganographic scheme that can effectively resist both RS and Chi-square analyses without sacrificing perceptual quality of the cover image. In the described steganographic technique, a pair of mutually complementary mappings, F1 and F-1, is used, leading to a balanced behavior of several statistical parameters explored by the two steganalytic approaches, therefore improved security. In other words, not only can the flipping between 2i and 2i + 1 be used, but also changes from 2i to 2i-1 or from 2i-1 to 2i are allowable. Although modification to the host pixels may affect the higher bit planes, the induced distortion to the host image is not increased compared to the simple LSB replacement technique. Extraction of the embedded information can still be accomplished by extracting the LSB plane as in the straight LSB method. The proposed method has low computation complexity and is easy to implement. Analysis of the effectiveness and experimental results are presented.