基于小波变换和离散余弦变换的数字水印方法

The method for watermarking based on wavelet transformation and discrete cosine transformation

提出一种以灰度或彩色图像作为水印、基于小波变换的数字水印算法 .该算法将宿主图像分解为小波系数 ,利用小波变换的自相似性构造QSWT选择并排序系数来嵌入水印 ,在嵌入水印之前对水印图像进行离散余弦变换 (DCT)并做Z扫描 ,使水印信息也做一个大致的排序嵌入在宿主图像中来增强算法隐蔽性和鲁棒性 .实验结果表明 ,本方法能有效地抵抗一些常见的水印攻击 .

The method for watermarking based on wavelet transform was proposed by using a gray or color image as watermark. The origin host image was decomposed into wavelet coefficients. Owing to the self-similitude of wavelet transform, the qualified significant wavelet trees (QSWT) were constructed and were sorted by I_l(x_k,y_k) to a QSWT sequence, QSWT_ k(x,y) . Before being embedded, watermark image was transformed to DCT coefficients and arranged by z-shape scan to enhance robustness of the approach and its imperceptibility. The experiment results indicated that the method can resist some typical watermarking attacks such as JPEG compressing, noise, filtering and so on.