基于图像特征点的数字水印算法

几何攻击作用在加载有水印的图像上，水印同步信息被破坏，导致水印检测失败。为了恢复已失去的同步信息，提出一种基于筛选尺度不变特征估计几何攻击参数的数字水印算法。首先提取图像的尺度不变特征，利用像素差的平方和筛选尺度不变特征，去除易受几何攻击影响的尺度不变特征,保证最小二乘法迭代运算快速收敛，迭代一次就能得到基本准确的几何变换参量；水印信息进行游程编码，在其码值对应的载体图像的DCT块内嵌入。实验结果表明，该算法能获得很好的图像质量，且能十分有效地抵抗各种几何攻击。

Digital watermarking algorithm based on image feature point

It might fail to detect watermarking now that geometric attacks perform on a watermarked image and destroy the synchronization of the watermark signals embedded in the image.To restore the lost synchronism,a novel method to estimate the geometric operation using sifted Scale-Invariant Feature Transform(SIFT)was proposed.According to Sum of Squared Differences(SSD)of the pixels,the suitable feature points were refined to ensure robustness of the least-squares solution.The least squares iterative was converge...