基于形态学梯度的DWT域自适应水印算法

An Adaptive Watermarking Algorithm in DWT Domain Based on Morphological Gradient

提出了一种基于形态学梯度的小波域自适应水印算法。利用形态学梯度,分析了小波包分解后的各子块的纹理分布及其强弱,并进行纹理排序。依据图像各子块自身纹理特征,自适应确定各子块阈值,选取大于其阈值的位置作为重要系数的位置进行水印信息的嵌入。然后,通过噪声可见函数(NVF)自适应调制各位置处的嵌入强度,在保证良好视觉掩蔽效果的基础上,采取最优的嵌入强度,更好的达到鲁棒性和不可见性的最佳效果。大量的实验结果表明,算法对常见的图像处理操作均有较好的鲁棒性。

An adaptive watermarking algorithm in the wavelet domain based on morphological gradient is proposed in this paper. Using morphological gradient, the distribution and the strength of the sub - block texture after the wavelet package decomposition are analyzed, and the texture is sorted. According to the texture feature of the sub - block, the sub - block threshold is determined adaptively and the position which is bigger than its threshold is selected as an important coefficient position where the watermarking is embedded. Then, the strength of the position is modulated adaptively through Noise Visibility Function （NVF） , which is the best strength to ensure good visual effect of masking to achieve the best effect between robust and invisibility. A large amount of experiments show that the proposed algorithm is effective and robust to common image processing operations.