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公有数字图像水印算法研究
Alternative TitlePublic Digital Image Watermarking Algorithms
任娟
Subtype工学硕士
Thesis Advisor谭铁牛 ; 王蕴红
2003-07-01
Degree Grantor中国科学院研究生院
Place of Conferral中国科学院自动化研究所
Degree Discipline模式识别与智能系统
Keyword公有水印算法 鲁棒性水印算法 图像认证 版权保护 Public Watermarking Robust Watermarking Image Authentication Copy Protection
Abstract数字水印技术是近年来人们研究的热点之一。随着研究的深入和实际应用 的需求,人们发现公有水印可以直接对待测图像进行检测,所以最近这方面的研 究得到了广泛的开展。本文根据数字水印实际应用的需求,研究分析了公有水 印算法面临一些实际问题,从公有鲁棒水印、半脆弱水印和完全脆弱水印三个 层次上展开研究,并针对目前没有解决的难点问题提出了一些解决方案。本文 中主要的工作和贡献有: ①提出了一种基于扩频思想的公有鲁棒水印算法。该算法利用了图像的离散 余弦变换(DCT)系数在图像经过尺度变换前后的变化规律,可以在图像 中嵌入有意义的版权保护信息。水印的提取独立于原始图像和其它条件, 并且可以直观地判断水印是否存在。这种算法不但可以抵抗一般的信号处 理攻击如压缩、滤波等,而且能够很好的抵抗尺度攻击。与现有的一些算 法相比,该算法降低了计算复杂度,并且扩充了可嵌入水印信息的容量。 ②提出了一种基于感兴趣区域的图像认证与自恢复半脆弱性水印算法。该算 法将图像分为两部分:感兴趣区域和背景区域。算法首先利用了基于4×4 分块的算法对感兴趣区域进行编码,然后利用映射函数将此码流嵌入到背 景图像的离散余弦变换系数中。该算法可以对整幅图像进行完整性认证, 同时,对被恶意篡改的感兴趣区域也能很好地恢复原始信息。 ③提出了一种基于双水印的完全脆弱性水印算法,将图像认证、图像恢复与 版权认证相结合。这里双水印算法是先将图像的标志、序列号等有关信息 嵌入到一幅灰度图像中,然后将得到的水印图像作为水印嵌入到宿丰图像 中。采用了HASH函数和置乱方法,可以抵抗对图像的各种篡改攻击。
Other AbstractIn recent years, digital watermarking technique has become an active research topic. People find that it is inconvenient to extract watermarks with the original image, so public watermarking algorithm has been discussed widely. In this thesis, we study how public watermarking solves application problems, and propose some algorithms to solve the difficulties in public watermarking such as scaling attack, VQ attack etc. The main contributions of this thesis include the following : ① We have proposed a public robust algorithm based on spread spectrum. The basic principle of the algorithm is derived from the relationship between the DCT coefficients of images before and after scaling. Watermark extraction is independent of the original image or any other conditions. Semantically meaningful watermarks can be embedded into a host image. This approach can resist not only common signal processing attacks such as compression and filtering etc, but also scaling attacks as well. ② We have proposed a self-recovery algorithm based on regions of interest. This algorithm divides a host image into two parts: regions of interest and regions of background. We code the regions of interest based on 4× 4 blocks, and embed these codes into the DCT coefficients of the background by a novel mapping function. Our scheme can authenticate the whole image, and at the same time, if the region of interest is tampered maliciously, the scheme can recover the original content in good quality. ③ We have introduced a double-watermarking algorithm to authenticate in- ages, recover the original image content, as well as to protect copyright. This technique firstly encodes a serial number in a logo, and then inserts this logo into an original image. This algorithm can detect malicious tamper and recover the original image content clearly.
shelfnumXWLW712
Other Identifier712
Language中文
Document Type学位论文
Identifierhttp://ir.ia.ac.cn/handle/173211/6794
Collection毕业生_硕士学位论文
Recommended Citation
GB/T 7714
任娟. 公有数字图像水印算法研究[D]. 中国科学院自动化研究所. 中国科学院研究生院,2003.
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