一种改进的利用像素差值的数据隐藏方法

本文介绍了一种新的,利用数字图像相邻像素的差值进行数据隐藏的方法.数字图像被分成互不重叠的2（2的连续的小快.分别计算水平和垂直方向的2像素的灰度差值.将所有可能的差值分成几个区间,并且给据人眼对灰度图像的敏感特性来划分这些区间.为了隐藏数据,用和原来的像素差值在同一个区间的一个新的差值来代替原来的像素差值.隐藏的数据能够从隐藏数据后的图像中恢复而不需要原始图像.此外,选择2（2的小块进行隐藏的顺序是伪随机的,从而有很高的保密性.模拟结果表明,这种方法比用图像像素的最低有效位（LSB）进行隐藏的方法[1]在视觉上更不容易察觉,并且一般的检测方法[4,5]对本文方法无效,而相比于仅利用水平方向像素差值进行隐写的方法[2],本文提出的方法有效提高了数据隐藏的容量.

An improved steganographic method by pixel-value differencing

An improved steganographic method for hiding data into a digital image is proposed. A digital image is divided into non-overlapping blocks with two-pixel height and two-pixel width. Two difference values are calculated from values of the four pixels in each block vertically and horizontally, respectively, All possible difference values are classified into a number of ranges. The selection of the range intervals is based on the characteristics of human visions sensitivity. The difference value then is replaced by a new value to hide data. The embedded data can be extracted from the resulting stego-image without referencing the original cover image. Moreover, a pseudorandom mechanism may be used to achieve secrecy protection. Experimental results show that the stego-image by the proposed method is more imperceptible than those yielded by simple least-significant-bit replacement methods. The proposed method is immune to some common statistical attacks. Comparative to the method in [2], its improvements increase the capacity.