一种基于模版的抗仿射变换数字水印算法

文中提出了一种基于模版匹配的抗仿射变换的数字水印算法。首先对要嵌入的消息进行RS纠错编码，以增加水印提取时的抗噪能力，并在傅里叶普中频的环上且靠近十字架附近的矩形区域中嵌入水印。然后使用一个单向HASH函数来确定图像DFT变换后水印嵌入具体位置。用两条线段作为模版嵌入图像DFT变换后再做极坐标变换的域中，水印的检测及提取则采用相关系数检测。实验结果表明该算法对JPEG压缩和各种几何变换都具有较好的鲁棒性。

Affine Resistant Digital Image Watermarking Based on Template Matching

This paper proposes an affine-resistant digital image watermarking based on template matching. First, the message to be embedded is coded by using RS codes to enhance the resistance capability of noise. Watermark is embedded on the mid-frequency spectrum, and the positions are considered in a rectangle which is symmetric to one side of the Cross, while the specific embedded positions are determined by a one-way hash function. Two structural template lines are then added in the polar coordinate system for detecting any combination of the geometrical distortions. The detection and extraction is based on correlation between the embedded and recovered watermarks. The experimental results indicate that this technique has a good performance when undergoing geometrical attacks and JPEG compression.