Color component 3D Arnold transform for polychromatic pattern recognition

We propose a novel method for polychromatic pattern recognition based on color component 3D Arnold transform. Three color components (for example RGB) are first transformed into three chaotic images by the use of 3D Arnold transform. And then any one of the chaotic images is chosen as the input image of the JTC to be recognized. As a result, strong color discrimination capability is achieved and common color images as well as some special color images can be recognized, while still preserving compact system and easier analysis of the output. Numerical results demonstrate the feasibility and effectiveness of the proposed method.     

Color image encryption by using Arnold transform and color-blend operation in discrete cosine transform domains

A color image encryption algorithm is designed by use of Arnold transform and discrete cosine transform (DCT). The RGB components of the color image are scrambled by Arnold transform at the aspect of pixel sequence. The scrambled RGB components are exchanged and mixed randomly under the control of a matrix defined by random angle. DCT is employed for changing the pixel values of color image. In this encryption scheme the operations mentioned above are performed twice continuously. The parameters of Arnold transform and the random angle serve as the key of the color image encryption method. Some numerical simulations are made to test the validity and capability of the color encryption algorithm.     

一种Arnold变换的改进方法

提出对于正方形数字图像,对离散化的Arnold变换进行反变换推算,反变换是通过对方程组求解得到的。并且对Arnold变换进行了改进,改进后的Arnold变换置乱原图像后所需的恢复时间比原Arnold变换和利用反变换的图像恢复时间快,周期更短,呈非线性关系。     

基于DCT的大容量二值水印嵌入新算法

传统的基于DCT变换的二值水印嵌入算法通常是在分块系数矩阵中选择一对中频系数实现1bit水印信息的嵌入,水印嵌入容量有限,为提高载体图像的安全性,提出了一种新的基于DCT的大容量二值水印嵌入算法.本算法首先对二值水印图像进行Arnold置乱加密处理,其次对所选取的载体图像进行分块DCT变换,然后选择4个中频系数进行排序,充分利用两两之间的3个差值关系实现水印的嵌入.若待嵌入水印位为0,通过改变系数值使得差值大于或等于阈值A,若待嵌入水印位为1,通过改变系数值使得差值等于阈值B,最终使得每块选择4个系数值实现了3bit二值水印信息的嵌入,水印嵌入容量大大优于传统方法.仿真实验表明,本算法实现了大容量水印的嵌入与提取且抵抗图像裁剪、图像加噪、JPEG压缩等攻击效果较好.     

A robust image watermarking technique using SVD and differential evolution in DCT domain

In this paper we applied differential evolution (DE) algorithm to balance the tradeoff between robustness and imperceptibility by exploring multiple scaling factors in image watermarking. First of all, the original image is partitioned into blocks and the blocks are transformed into Discrete Cosine Transform (DCT) domain. The DC coefficients from each block are collected to construct a low-resolution approximation image and apply Singular Value Decomposition (SVD) on this approximation image. After that watermark is embedded by modifying singular values with the singular values of the watermark. The role of DE algorithm is to identify the best multiple scaling factors for embedding process in order to achieve the best performance in terms of robustness without compromising with the quality of the image. To enhance the security, watermark is scrambled by Arnold transform before embedding. Experimental results show that the proposed scheme maintains a satisfactory image quality and watermark can still be identified from a seriously distorted image.     

离散Arnold变换改进及其在图像置乱加密中的应用

为了改善传统二维Arnold变换用于图像置乱加密的效果,提出了离散Arnold变换的改进方法,并将其用于图像置乱加密测试研究.该方法利用现有离散标准映射的构造思想,将传统离散二维Arnold变换表达式中第一个变换表达式所对应变换结果非线性融入第二个变换表达式,实现经典离散二维Arnold变换的非线性去拟仿射化修改,以便快速改善图像置乱加密效果.数学证明改进方法不再保持现有离散二维Arnold变换所具有的拟仿射不变性,但是改进变换仍是一种具有周期性的可逆映射,将其用于图像置乱加密时,利用其周期性或逆变换能恢复置乱前原图像.大量实验结果表明,本文所建议的改进方法是有效的,相比现有的离散Arnold变换更具有实用价值意义.     

基于相关性的图像置乱程度衡量方法

为了对数字图像置乱程度进行有效的衡量,根据数字图像相邻点之间像素值的相关性随像素点位置的变化而改变这一原理,提出了一种基于各相邻点之间像素值差异的图像置乱程度衡量新算法.并由Matlab软件仿真结果表明,该方法可以清楚的表现出图像置乱程度与置乱次数的关系.     

与三阶特征值问题相联系的Hamiltonian系统

利用特征值问题的非线性化方法,讨论了与三阶特征值问题相联系的Hamiltonian系统,并根据Arnold定理与生成函数方法,证明其在Liouville意义下是完全可积的.然后,借助位势函数与特征函数之间的关系,给出发展方程族的对合解.     

A numerical study of the topology of normally hyperbolic invariant manifolds supporting Arnold diffusion in quasi-integrable systems

We investigate numerically the stable and unstable manifolds of the hyperbolic manifolds of the phase space related to the resonances of quasi-integrable systems in the regime of validity of the Nekhoroshev and KAM theorems. Using a model of weakly interacting resonances we explain the qualitative features of these manifolds characterized by peculiar ‘flower-like’ structures. We detect different transitions in the topology of these manifolds related to the local rational approximations of the frequencies. We find numerically a correlation among these transitions and the speed of Arnold diffusion.     

C. V. Raman and the Discovery of the Raman Effect

In 1928 the Indian physicist C. V. Raman (1888-1970) discovered the effect named after him virtually simultaneously with the Russian physicists G. S. Landsberg (1890-1957) and L. I. Mandelstam (1879-1944). I first provide a biographical sketch of Raman through his years in Calcutta (1907-1932) and Bangalore (after 1932). I then discuss his scientific work in acoustics, astronomy, and optics up to 1928, including his views on Albert Einstein's light-quantum hypothesis and on Arthur Holly Compton's discovery of the Compton effect, with particular reference to Compton's debate on it with William Duane in Toronto in 1924, which Raman witnessed. I then examine Raman's discovery of the Raman effect and its reception among physicists. Finally, I suggest reasons why Landsberg and Mandelstam did not share the Nobel Prize in Physics for 1930 with Raman. RID="*" ID="*"Rajinder Singh is a Diplom-Physiker who is currently working on his doctoral thesis on C. V. Raman and the discovery of the Raman effect in the Department of Higher Education and History of Science in the Faculty of Physics at the University of Oldenburg, Germany.