研究了数字图像中水印信息添加的问题.针对以往基于空间域水印图像加载保密性差、容易受到噪声干扰等缺陷,提出了一种利用随机产生的差分矩阵进行水印加载与提取的算法.首先利用随机数构造一个随机矩阵；然后将原始图像与构造的随机矩阵进行差分运算,通过线性叠加函数,将待添加的水印信息添加到差分短阵图像中,从而实现了水印加载.该方法由于利用了随机差分矩阵,因此有很好的安全特性,并能很好地实现显式或者隐式水印信息的加载.实验结果显示,该方法能在不影响原始图像的观感条件下实现水印的有效添加,并且所添加的水印图像能有效地防止噪声的干扰,实现准确的水印加载和提取.%This paper proposed a new algorithm to embed watermark into a digital image in spatial domain. Normally, the watermarking in spatial domain suffered from noises, it presented a differential matrix, which generated using several random keys, to construct the result watermarked image. The first step of proposed method was to generate 4 random keys which used to subtract from different regions of original image. Then it added the watermark image into differential matrix using a linear function. The random keys ensured the security of the system and linear combination of differential image and watermark image made the extraction easier than previous methods. Experiments show the proposed method is effectively prevent the noise interferes with, achieving accurate loading and extracting the watermark.
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