一种新的图像自适应水印算法

Novel Image-adaptive Watermarking Algorithm

数字水印是数字媒体版权保护的一种有效方法.提出了一种新的基于DCT(DiscreteCosineTransform)域的盲图像自适应数字水印算法.该算法利用视觉系统HVS(HumanVisualSystem)特性和图像的局部特点,自适应地选择量化步长对图像各个分块的直流分量通过量化来嵌入水印,同时为了弥补在感知容量小的分块直流分量上水印嵌入强度的不足,利用照度掩蔽特性对该分块的部分低频系数也自适应地嵌入同一水印信号,从而使水印的稳健性和不可见性之间达到很好的平衡.水印的提取不需要原始图像.实验结果表明该算法实现的水印具有良好的不可见性,并对常见的几种图像处理和噪声干扰也具有很好的稳健性,其性能优于其它文献上的相近算法.

Digital watermarking is an effective method to provide copyright protection for digital media. A blind image- adaptive watermarking algorithm based on DCT domain is presented. The algorithm selects adaptively the step size of quantization to embed the watermark bits by modifying DC components via the human visual system model and local characteristics of image; at the same time some AC components of the blocks with less perceptual capacity are also modified to embed the same watermark bits by using quantization. Thus the relation between robustness and imperceptibility can be well balanced. The algorithm recovers the watermark without any reference to the original image. Compared with the similar algorithm reported in the literature, this method can give better image quality and is better robust against noise and commonly used image processing techniques.