【作者】 张伟东；

【导师】 端木春江；

【作者基本信息】 浙江师范大学 ， 计算机软件与理论， 2011， 硕士

【摘要】 随着数字化信息时代的到来,越来越多的数字化产品普及到了人们的日常生活。虽然数字化技术对信息的处理、传播和复制了提供极大的便利,但同时它也带来了一些负面效果,如版权盗用、恶意篡改和非法拷贝等问题。数字图像作为多媒体信息重要载体,对它的版权保护和内容真实性的认证技术的研究具有重要的理论与实际应用价值。为此,本论文对这一课题进行了深入的研究,研究工作如下：(1)对哈尔小波变换、Logistic混沌和Arnold置乱的理论在图像处理应用上进行了研究,并给出了在计算机上对哈尔小波变换、Logistic混沌及Arnold置乱的模拟结果。(2)在零水印技术基础上,结合小波变换后对于图像低频信息保留原图像能量高的优点,本论文提出了一种利用拓展的版权水印和混沌密钥的图像零水印算法。该算法首先将由版权水印利用混沌密钥加密,然后利用图像特征稳定性,将原始图像生成图像特征矩阵与混沌加密后的用户版权水印矩阵进行相关运算生成版权认证矩阵,接着将版权认证矩阵、时间戳、图像信息保存到版权数据库以用作版权认证。实验表明,所提出的方案在对抗图像的常规攻击及裁剪攻击下具有良好的鲁棒性。(3)根据自嵌入图像认证思想,本论文提出一种新的基于哈尔小波变换的半脆弱图像数字水印算法。该算法首先利用峰值信噪比确定图像可嵌入水印的最大容取值,然后根据可嵌入水印的最大容取值将基于原始图像内容的构造的水印量化地嵌入小波变换之后的低频系数2*2分块中,最后将对接收到的图像内容和提取的水印进行分块相关性比较,检测图像内容完整性和真实性。实验表明,该算法对图像的抗压缩、噪声、滤波等常规攻击中具有较强的鲁棒性,能准确地实现篡改的检测,具有可行性和实用性。更多还原

【Abstract】 With the advent of the digital information age, more and more digital products become popular in our Daily life. Although digital information technology of copying, and reproducing provides great convenience, meanwhile it brings some negative effects, such as the copyright theft and malicious tampering and illegal copying. As digital image is an important carrier of multimedia information, its copyright protection and authentication technology have important theoretical and practical value. Thus this paper conducts the research in this area and the contents are listed in the following(1) Firstly, it studies HAAR wavelet transform, Logistic chaos and Arnold scrambling in Image processing, and presents simulation results of HAAR wavelet transform, Logistic chaos and Arnold scrambling.(2) Based on non-watermark techniques, and the advantage of high energy of the original image after wavelet transform, this paper proposes a watermarking algorithm using the expandability of the copyright watermark technique and chaotic keys. Firstly, the algorithm encrypts the copyright image watermark by using chaos keys, then uses the stable features of the original image, and the characteristic matrix generated by the original image and copyright image watermark matrix with chaotic key encryption. Then, it makes some kinds of calculation for generating authentication matrix. Finally the authentication matrix, time stamp, and image information are saved to the watermark database for copyright authentication. Experiments show that the proposed scheme is robust against the conventional image attacks and the cutting attack.(3) According to the idea of embedded image authentication, this paper presents a new half fragile image watermarking algorithm based on HAAR Wavelet transform. Firstly, this algorithm determines the maximum value which the image can embed according to the needed peak signal-to-noise ratio value (PSNR) before and after image embedding. Then according to the maximum watermark capacity, the watermark image is embedded based on the HAAR wavelet-transform of the original image in the 2 * 2 low-frequency coefficients. Finally the embedded image content is extracted based on correlation comparison, detection images content integrity and authenticity. Experiments show that this algorithm is robust to image anti compress, noise, and filtering in conventional attacks, can accurately detect which region is tampered, and has the feasibility and practicability.更多还原