基于伪Zernike矩的抗几何攻击图像水印

针对几何攻击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,提出了一种抗几何攻击图像水印算法(GWPZM).首先计算图像的伪Zernike矩,选择适宜于嵌入水印的矩进行幅度改变量测试.筛选出最优矩集合,根据水印比特自适应地修改集合中的矩,并对差矢量进行伪Zernike矩重构,通过将重构图像在空域迭加到原始图像中嵌入水印.水印检测时,首先计算受攻击图像的伪Zernike矩,以最优矩集合作为密钥,通过与原始图像比较矩的幅度提取水印.实验结果表明,GWPZM算法能够抵抗旋转、缩放攻击、二者组合攻击以及JPEG压缩、噪声等常规攻击.

Geometrically Robust Image Watermarking Based on Pseudo-Zernike Moments

A geometrically robust image watermarking algorithm(GWPZM)is proposed by using the rotation invariant property of pseudo-Zernike moments.The pseudo-Zernike moments of the cover image are first computed.Those suitable for watermark embedding are selected and tested according to their magnitude changes after being modified.Optimal moment set is determined and the moments within it are modified according to the random watermark bits.The difference vector is reconstructed and added to the cover image in spatial domain to obtain the watermarked image.In detection,the pseudo-Zernike moments of the possibly attacked images are computed and the watermark is extracted by comparing the magnitudes of selected moments with the optimal moment set as the key.Experimental results show its robustness to rotation,scaling,combined attacks,as well as common attackes such as JPEG compression and added noise.