基于DCT的安全抗剪切攻击数字图像水印算法
Digital Image Watermarking Algorithm Based on DCT Security against Shear Attack

为解决嵌入水印后不抗剪切攻击的问题，围绕Arnold置乱，结合分块的离散余弦变换(Discrete Cosine Transform, DCT)水印算法，本文提出了基于DCT域的安全抗剪切攻击的盲数字水印算法。首先将水印图像进行置乱加密，并对它进行上下对换、左右对换得到变换水印，进行二次水印嵌入，提取时对两个水印进行重组拼接来得到完整水印，从而提高鲁棒性。实验结果表明，在二次嵌水印后，只要剪切面积不超过图像大小的1/2，该算法对剪切攻击就有100%的抵抗力，并且透明性也能得到很好的保证。
To address the issue of not being resistant to cropping attacks after embedding watermarks, this paper proposes a secure blind digital watermarking algorithm based on Arnold and the block wise Discrete Cosine Transform (DCT) watermarking algorithm, which is secure against cropping attacks in the DCT domain. Firstly, the watermark image is scrambled and encrypted, and it is swapped up and down and left and right to obtain the transformed watermark, and the secondary watermark is embedded. When extracting, the two watermarks are reassembled and spliced to obtain the com-plete watermark, thus improving the robustness. The experimental results show that the algorithm has 100% resistance to the shear attack, and its transparency can be well guaranteed, as long as the shear area does not exceed 1/2 of the image size after the secondary watermarking.