毕业设计（论文 ）-基于二维Arnold变换非等长数字图像置乱算法研究.doc

摘 要 随着网络技术的发展，越来越多的图像信息在网络中传输，使得图像信息的安全性尤为重要。保障图像信息安全性最常用的方法就是图像置乱，图像置乱有许多置乱算法，Arnold变换因其简单而广为使用。现在对于Arnold变换通常应用于正方形图像置乱的研究。而对于高宽不等的矩形图像，现有的方法是将Arnold变换推广后对高宽满足一定条件的图像进行置乱，但它不适用于所有高宽不等的图像；另一种方法是将矩形图像按长边扩充为正方形图像后用Arnold变换进行置乱，但该算法改变了图像的属性。针对现有算法存在的问题提出了一种新颖的方法，该方法采用划分的方式使得非等长图像可应用Arnold变换进行图像置乱。对非等长图像只需根据高与宽计算出划分时的重合区域，按短边为边长对非等长图像划分为几个正方形图像，然后对每个正方形图像依次运用Arnold变换进行置乱。置乱后的图像从反方向依次对划分的正方形图像运用Arnold反变换将图像恢复。最后，在MATLAB下对算法进行了仿真实验。实验结果表明，该算法具有很好的置乱效果，同时该算法可广泛应用于非等长图像的置乱变换过程。 关键词：数字图像；图像置乱；Arnold变换；非等长图像 ABSTRACT With the development of network technology, more and more image information is transmitted in the Internet, which makes the security of image information particularly important. The most common method to ensure the security of image information is image scrambling. There are many hashing algorithms, of which Arnold transform is widely used for its simplicity. Now Arnold transform is applied in the study of image scrambling of square. For the rectangular images with different height and width, the current approach is to scramble images which meet the required height and width. But it does not apply to all images especially with different height and width. Another method is to expand rectangular images to square by lengthen the edge. Then using Arnold transform to scramble the square image. But this hashing algorithm has changed the attribute of the image. Due to the problems existing in the current algorithm, a novel method has been put forward, which applies a way of dividing tubes to make images use Arnold transform. For those images with different length, we only need to calculate superposition region, and then use Arnold transform to scramble each square image. The scrambled image should be restored by using reverse Arnold transform from reverse direction. In the end, the author carried out simulation experiment under MATLAB. The results show that this algorithm has very good effect on scrambling. At the same time, it can be widely used in the process of sc