基于3D-DCT和SVD的鲁棒彩色图像水印算法

A robust color image watermarking algorithm based on 3D-DCT and SVD

在数字图像水印领域,水印算法主要集中于灰度图像,且提出的大部分彩色图像水印算法往往仅在亮度分量或在彩色图像的每一通道中嵌入水印,未能充分利用彩色图像的冗余空间,影响了水印的透明性和鲁棒性。针对此问题,提出了一种新颖的基于三维离散余弦变换和奇异值分解的彩色图像水印算法。算法先对水印图像进行预处理和对彩色图像进行互不重叠的分块;其次对每一分块进行三维离散余弦变换;最后选择对三维离散余弦变换系数的第一分量进行奇异值分解。嵌入水印时,对三维离散余弦变换系数第一分量的最大奇异值和第二分量分别采用量化和关系的嵌入方法嵌入水印。提取水印时,分别采用量化和关系提取算法提取水印并进行比较,选取相似值高的水印图像作为最终提取的水印。实验结果表明,提出的算法具有较好透明性的同时,具有抵抗常规信号处理和模糊、扭曲及锐化等攻击的能力。

In the field of digital image watermarking, watermarking algorithms mainly focus on gray images, whereas most of color images watermarking algorithms usually embed watermarking only in the luminance component or in each channel of color image separately. These algorithms are unable to make full use of the redundant space of color images, thus affecting the watermarking^s transparency and ro- bustness. To solve these problems,we propose a novel color image watermarking algorithm based on the three-dimensional discrete cosine transform （3D-DCT） and the singular value decomposition （SVD）. Firstly, the watermarking image is pre-processed and the color image is subdivided to non-overlapping blocks. Secondly, we perform the 3D-DCT for each block and apply the SVD in the first component of the 3D-DCT coefficients. We use the quantization method and the relationship method to embed water- marking in the largest singular value and the second component of 3D-DCT coefficients respectively at the embedding watermarking stage. At the watermarking extraction stage, we extract the watermarking image using the quantization method and the relationship method separately and the results are com- pared. The result with higher correlation value is chosen as the final extracted watermarking. Experimental results show that the proposed algorithm has good transparency and the ability to resist common signal processing and fuzzy, distorted, sharpening attacks.