一种新的小波域正交数字水印方案

A New DWT Orthogonal Digital Watermarking Algorithm

提出一种基于人眼视觉模型、小波变换和正交向量的数字水印方案.首先对原始图像进行8×8的分块,然后对每小块进行小波变换,进而对水印图像进行调制,并加入到原始图像中,形成带水印图像,最后进行小波反变换得到含有水印的图像.在水印检测过程中,根据实际需要提出了非盲水印和盲水印两种检测方案.根据正交向量的特点通过假设检验的方法提取水印.实验表明,这种方法能有效检测出水印图像,并对常见的水印攻击(如裁剪、JPEG压缩等)具有良好的鲁棒性,尤其对信号增强或减弱抗攻击性强.

This paper presents a new perceptual digital watermarking scheme based on human vision system, discrete wavelet transform and orthogonal vector. The original gray image is first divided into 8 × 8 blocks, and then 8 ×8 blocks are permuted. A 1-level digital wavelet transform （DWT） is applied to each 8 × 8 block. Each watermark bit is modulated by orthogonal vector, then the watermark is added to the original image. Finally the IDWT is performed to form the watermarked image. In the watermarking detection process, two detection algorithms are proposed. By hypothetical testing, the watermark can be extracted exactly. The experimental results show that the proposed technique successfully survives image processing operations, image cropping, and the Joint Photographic Experts Group （JPEG） lossy compression. Especially, the scheme is robust towards image sharping and image enhancement.