为了提高隐写的安全性, 必须保持隐写前后图像的特征一致. 提出了一种保持直方图特性的隐写算法. 首先, 对像素直方图进行分组, 通过计算定量失真时的最大嵌入数据量, 得到每个像素的修改概率, 并利用STC(syndrome trellis codes)确定需要修改的像素位置; 然后,根据直方图分组情况对需要修改的像素值进行组内和组间自适应调整, 实现秘密信息的嵌入,同时保持隐写前后图像的直方图变化最小. 实验结果表明, 在相同嵌入量的前提下, 该方法对直方图的改动远少于已有的隐写算法, 隐写图像视觉质量更好.
To enhance security of steganography, the characteristics of the image should be kept as far as possible. This paper proposes a steganography algorithm with histogrampreserving property. Firstly, the histogram of pixel values is grouped. By calculating the maximum payload under a given distortion, the modification rate for each pixel is found and the location of pixels is got that need to be changed by syndrome trellis codes (STC). Then embedding is performed by changing those pixels using adaptive intra-group and/or inter-group adjustments. The difference in histogram between the cover and the stegoimages is very small. Experimental results show that the proposed method makes less histogram change and gives better visual quality than existing methods under the same
embedding rate.
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