一种基于多尺度空间的图像水印算法

当前数字水印对常见的图像处理攻击如高斯噪声、中值滤波、有损压缩等具有较强的抵抗能力，但其抵抗剪切、缩放等几何攻击的能力较差。因此，为提高数字水印的鲁棒性，结合尺度不变特征变换算子和视觉感知模型，提出一种基于不变特征的水印嵌入方法。基于广义高斯分布模型对小波系数进行刻画，并根据二值假设检验理论确定水印的检测阈值，由此进一步给出水印虚警和漏警之间的工作特性曲线关系。实验仿真结果表明提出的水印方法在抗压缩、叠加噪声、缩放、剪切、旋转等攻击时具有较好的鲁棒性能。

An Image Watermarking Algorithm Based on Multi-scale Space

The existing image watermarking algorithm is of good robustness when against some common image processing attacks such as Gaussian noise, median filtering and lossy compression, etc. However, the robustness of watermark is poor when against some geometric attacks such as cropping and scaling, etc. Therefore, in order to improve the robustness of watermark, an embedded watermarking method is proposed based on invariant feature by combining the scale invariant feature transform and visual model. In the detection scheme, the probability density function of wavelet coefficients which in mid-frequency sub-band is modeled by the generalized Gaussian distribution model and the watermark decision threshold is determined by using the binary hypothesis theory. Furthermore, the receiver operating characteristic (ROC) curve between the probability of false alarm and the probability of detection is derived. Experimental results demonstrate that the proposed method is of good robustness when against some attacks such as JPEG compression, additive white Gaussian noise, scaling, cropping and rotation etc.