空间域和频率域相结合的数字水印

Combinational Image Watermarking in the Spatialand Frequency Domains

为了嵌入更多的水印数据和减小数字图像的失真,提出了一种新颖的空间域和频率域相结合的数字水印方法。根据使用者的需求和数据重要性,将水印图像分成两部分,分别嵌入到原始图像的空间域和频率域,并对嵌入不同尺寸的水印图像的结果进行比较。提出的水印方法具有以下优点:更多的水印数据被嵌入到原始图像中,因此容量增加;水印被分成两部分,使得安全性增加。对水印分离策略的复杂化,可增加攻击者重构水印的难度。另外,为了增强鲁棒性可对水印数据进行随机置乱操作以抵抗剪切等信号处理操作。

In order to provide more watermarks and to minimize the distortion of the watermarked image, a novel technique using the combinational spatial and frequency domains is presented in this paper. The splitting of the watermark image into two parts, respectively, for spatial and frequency insertion rehes on the user＇s preference and data importance. Experimental results provide the comparisons when different sized watermarks are embedded into a grayscale image. The proposed combinational image watermarking possesses the following advantages. More watermark data can be inserted into the host image, so that the capacity is increased. The splitting of the watermark into two parts makes the degree of protection double. The splitting strategy can be designed even more complicated to be unable to compose. Furthermore, to enhance robustness, a random permutation of the watermark is used to defeat the attacks of signal processing, such as image crops.