基于Tchebichef矩的抗几何攻击图像水印

Geometrically Robust Image Watermarking Based on Tchebichef Moments

针对几何攻击容易使常规水印算法检测失败的问题,利用Tchebichef矩出色的重构性能,结合图像归一化,提出一种基于Tchebichef矩的抗几何攻击图像水印算法GWTM。该算法在水印嵌入和提取之前对图像进行几何失真的归一化,根据Tchebichef矩系数的特点,进行矩幅度修改量测试,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,并对修改后的矩进行Tchebichef重构,实现水印的嵌入。水印提取时,以最优矩集合为密钥,通过与原始图像的Tchebichef矩幅度比较提取水印。实验证明,GWTM算法能够抵抗任意角度的旋转攻击、缩放攻击及常规的信号处理攻击。

Aiming to the question that geometric attacks desynchronize watermark detection to fail many watermark schemes, we present a new geometrically robust image watermarking scheme based on Tchebichef moments （GWTM）. Geometric distortions are first resynchronized by image normalization, and watermark insertion and extraction are implemented in normalized domain. To select a moment set fits watermark embedding using the property of Tchebichef moments. According to the magnitude changes of the above moment set after being modified, an optimal moment set is determined by test, and the moments within it are modified according to the random watermark bits. The modified optimal moment set is reconstructed to obtain the watermarked image. In detection, the watermark bits are extracted by comparing with the Tchebichef moments of original image with the optimal moment set as a key. Experimental results show that GWTM can efficiently resist rotation attacks of random angles, scaling attacks and common signal processing attacks.