【作者】 张姁；

【导师】 穆国旺；

【作者基本信息】 河北工业大学 ， 计算数学， 2007， 硕士

【摘要】 随着网络技术和数字通信技术的飞速发展,各种数字多媒体信息包括文本、图像、音频、视频等可以方便地在网络上传播,与此同时,如何保护这些数字产品的版权成为了一个亟待解决的问题.数字水印技术作为数字产品版权保护、内容认证等的一种有效途径,近年来受到了人们的广泛关注,成为了信息安全领域的一个新的热点.但是,目前文献中对于在彩色图像中嵌入灰度水印研究的还很少.由于在图像中嵌入灰度水印,嵌入的信息量大,因此,如何兼顾水印的不可见性和鲁棒性是一个具有挑战性的问题.本文根据人眼视觉特性,将小波变换方法和其它方法有机地结合,在兼顾水印不可见性和鲁棒性的前提下,提出了三种彩色图像灰度水印算法:提出了基于位分解和小波变换的彩色图像灰度水印算法,其基本思想是:对载体图像进行小波分解,并对水印图像进行位分解,对重要位进行扩频处理,将其嵌入在载体图像的低频和中频分量中,将不重要位直接嵌入到中频分量中,然后进行重构得到加水印后的彩色图像.提出了基于DCT压缩和小波变换的彩色图像灰度水印的算法,首先对水印进行JPEG压缩编码,并对载体图像进行小波变换,再根据载体图像的小波视觉掩蔽特性(JND)自适应量化嵌入.提出了基于小波分解的彩色图像灰度水印算法,对水印图像和载体图像均进行小波分解,将水印图像的低频分量进行扩频,并将其嵌入到载体图像的低频中,而将水印图像的高频分量嵌入到载体的中频分量中.本文通过仿真实验对上述算法进行了验证,实验结果表明,文中算法对叠加噪声、JPEG压缩、几何剪切等攻击均具有较好的鲁棒性,并且可以实现盲提取.更多还原

【Abstract】 The multimedia technology has become more and more important along with the booming development of network and digital communication technology. Various kinds of digital multimedia information including text, image, audio and video etc., have widely been distributed through network. At the same time, how to protect this copyright of digital information has become a question need to solve at once. Digital watermarking as the copyright protection and contents authentication of digital media has become an effectual way. Digital watermarking may be a good way to resolve the issue, so it has become a hot research topic and has drawn extensive attention in the field of the information saved. However the practical techniques in color image digital watermarking is lesser studied, especially for the embedding algorithm of grayscale watermarking signal. Because of the question of the gray-level watermark need more places to embed complicate information .Thus, it becomes a challenging question that how to deal with the invisibility and robustness of the digital watermark.In this article, considering the characteristic of human visual system, three gray-level watermark of color image digital watermarking algorithms based on the optimum combine of the wavelet transform and other methods were presented according to the deal with the invisibility and robustness of the digital watermark .A digital watermarking algorithm based on bit decomposition and wavelet transform .The basic thought of this algorithm is makes wavelet transform to the carriers image ,and makes bit decomposition to the watermarking image ,then chose the important bits to enlarge frequent and embed in the part of the median frequency and the low frequency weight of the carriers image .At on time embed the unimportance bits in the median frequency weight ,then construct again have the color image of the watermarking.Also we groped a digital watermarking algorithm based on DCT compression and wavelet transform .It first make JPEG compression and code to the watermarking image and make wavelet transform to the carriers image. According to JND embed the in the carriers image.Another digital watermarking algorithm based on wavelet transform is proposed. It makes wavelet transform to the carriers image and the watermarking image, and make the low frequency weight of the watermarking image enlarge frequent ,then embed in the low frequency weigh of the carriers image. It makes the high frequency weight of the watermarking image embed in the median high frequency weight. In this article, we have that watermarking algorithm imitated and simulation test, the experimental results show that the proposed watermarking scheme is robust for various attacks such as noise adding, JPEG compression and cropping.更多还原