一种基于离散余弦变换的数字水印算法

研究利用离散余弦变换(DCT)对静态灰度图像进行数字水印嵌入的算法,侧重点是嵌入水印的方式和方法。其原理为将水印和原图分别分割为若干块后转换到DCT域再分别对应嵌入,但对水印嵌入的位置有一定要求,即将变化后的水印信息嵌入到图像的中频靠近低频的部分,使水印嵌入后有隐藏性和抗攻击性。实验结果表明在一定条件下水印能很好地隐藏在原图中,且对图像的涂抹、剪切攻击有一定的抵抗性。

A Digital Watermarking Algorithm Based on Discrete Cosine Transform

This article researches on the algorithm of embedding digital watermarking in static gray images based on discrete co- sine transformation （ DCT）, and focuses on the ways and means of embedding watermarking. The algorithmic principle is dividing the watermarking and original images into blocks, converting the blocks to DCT domain, and embedding them correspondently. However, the watermarking must be embedded in a certain place, that is embedding the watermarking to images in some of the in- termediate frequency near low frequency part. The purpose is to make the embedded watermarking better hidden and resistant to attack. Experimental results show that under certain conditions, the watermarking can be well hidden in the original image with a certain degree of resistance to attack of smear or shear.