结合代数多重网格的钻石编码隐写算法

针对隐写算法安全性的问题，提出一种结合代数多重网格（AMG）的钻石编码（DE）隐写算法。首先，通过AMG方法将图像的像素点分成粗细网格两个部分。然后，结合DE把机密信息分别嵌入到粗细网格两个像素序列中。其中，粗网格部分像素的改变对整幅图像的质量影响较小，而细网格部分像素的改变对整幅图像的质量影响较大。又因为DE的k值跟信息隐藏容量密切相关，随着k值的增加像素改变量变大，所以用DE嵌入的过程中，粗网格部分选择的k值不小于细网格。最后，选择DE的k值等于1与2，提出了三种隐写方案。与最低有效位（LSB）置换、随机LSB匹配、DE算法和自适应边缘检测算法进行比较，实验结果表明，三种隐写方案的一阶Markov安全指标皆优于其他对比隐写算法。

Diamond encoding steganography algorithm based on algebraic multigrid

Concerning the problem of security for steganography algorithm, a Diamond Encoding (DE) steganography algorithm based on Algebraic MultiGrid (AMG) was proposed. Firstly, an image was divided into two parts of coarse grid and fine grid by the AMG method. Then, the confidential information was embedded into the two part pixels of coarse grid and fine grid by DE method. The change of pixels in coarse grid part has little influence on the whole image quality, while the change of pixels in fine grid part has the great effect on the whole image quality. And the k value of DE is associated with the capacity of information hiding closely, the pixels change greater with the k value increasing. Therefore, in the embedding process with DE, the k value of the coarse grid part is not less than that of the fine grid part. Finally, when the k value of DE was chosen to 1 and 2, three kinds of steganography scheme were proposed. The proposed algorithm was compared with Least Significant Bit (LSB) replacement, random LSB matching, DE algorithm and adaptive edge detection algorithm. The experimental results show that, the first-order Markov security metric of the proposed algorithm is superior to other contrasted steganalysis algorithms.