基于伪Zernike矩的图像自适应RST不变水印

Image adaptive RST invariant watermark based on pseudo-Zernike moments

针对旋转、缩放和平移等几何攻击能够破坏水印检测的同步性,容易使常规水印算法检测失败的问题,利用图像伪Zernike矩的幅度具有旋转不变的性质,结合奇偶量化,提出了一种图像自适应旋转、缩放和平移不变水印算法.首先计算图像的伪Zernike矩,选取适宜于生成水印的矩,再对所选的矩幅度进行奇偶量化生成自适应水印序列.检测时,利用归一化汉明函数判断水印的相似度.实验结果表明不变水印算法可以抵抗任意角度旋转攻击和缩放攻击.对JPEG压缩,噪声,滤波等常规攻击,提取水印的相似度均在0.95以上.

Rotation, scaling and translation （RST） attacks can desynchronize watermark detection, thus making many watermarking systems fail. In this paper, an image adaptive RST invariant watermark （AWPZM） is proposed by using the rotation invariant property of pseudo-Zernike moments and odd-even quantization. Pseudo-Zernike moments of the original image are computed firstly,and those suitable for watermark generation are selected. Then, their magnitudes are odd-even quantized to generate the watermark. In detection, the normalized hamming function is employed to weigh the similarity of the watermark. Experimental results show its robustness to rotation and scaling. For traditional attacks such as JPEG compression, added noise and filtering, the similarities are all above 0.95.