一种基于图像特征的彩色图像水印算法

摘要

To improve the ability of watermarking algorithm in resisting geometrical attacks, we propose an image feature-based watermarking algorithm for colour images.First, it uses Speed Up Robust Features ( SURF) algorithm to extract steady feature points in the image, and constitutes SURF feature description operator for it, which makes the extracted feature points have scale invariance;Secondly, it obtains local feature region according to the adaptivity of the feature scale and normalises it;Then the algorithm applies slant transformation on local feature region, and gets the frequency coefficient in it; Finally, it completes the watermark embedding by combining singular value decomposition (SVD) algorithm.Experimental results show that the image with the watermark embedded still has higher similarity of its extracted watermark to the original one’ s after suffering the noise and geometrical attacks, this algorithm has quite good robustness.%为了提高水印算法的抗几何攻击能力，提出一种基于图像特征的彩色图像水印算法。首先利用加速鲁棒性特征SURF （ Speed-Up Robust Features）算法提取出图像中稳定的特征点，并为其构造SURF特征描述算子，使提取出的特征点具有尺度不变性；然后根据特征尺度的自适应性获得局部特征区域并对其进行归一化处理；之后对局部特征区域进行斜变换，并获得其中频系数；最后结合奇异值分解SVD（ Singular Value Decomposition）算法完成水印的嵌入。实验结果表明，嵌入水印后的图像在经过噪声以及几何攻击后，其提取的水印与原水印仍具有较高的相似度，该算法具有较好的鲁棒性。