基于整数DCT变换的新水印算法

鲁棒性及掩蔽性是衡量数字水印算法性能的重要指标。为了用较低算法复杂度使数字水印具有较好的鲁棒性与掩蔽性,提出了一种基于整数DCT变换的新的鲁棒水印算法。该算法利用DCT变换的整数特点,首先对频域嵌入系数进行定量分析,找出适合嵌入的系数与嵌入阈值的大小关系,接着提取每个图像块的DC系数组成一幅新图,选择新图中具有复杂纹理的图像块再次进行整数DCT变换,最后将水印信号嵌入到这些图像块域的系数中。仿真实验结果表明,新算法既保证了水印的掩蔽性,又同时具有很好的鲁棒性,对JPEG压缩、噪声、滤波等攻击都具有很好的免疫能力,即使是在马赛克攻击下也能提取出水印图像。

A Novel Image Watermarking Algorithm Based on Integer DCT

Robustness and invisibility are used to evaluate the performance of the watermark algorithm.In order to design a complicated scheme with both preferable robustness and invisibility with low complexity,in this paper,a new watermarking based on Integer DCT scheme is proposed.At first we studied the integral transform characteristic of the frequency coefficients,to find out the coefficients which are fit to be embedded and the relation of theirs embedded threshold.Then we formed a new image by extract each block DC coefficient,and select out numbers of the blocks with complex texture.At last,by Integer DCT,the digital watermark signals were embedded into the frequency coefficients of the theses blocks.Experimental results show that the proposed watermarking scheme ensures that the invisibility of watermark,and have good robustness against various attacks such as JPEG compression,noise,filter and so on,even if under the mosaic attack.