Exposing Digital Forgeries From JPEG Ghosts

When creating a digital forgery, it is often necessary to combine several images, for example, when compositing one person's head onto another person's body. If these images were originally of different JPEG compression quality, then the digital composite may contain a trace of the original compression qualities. To this end, we describe a technique to detect whether the part of an image was initially compressed at a lower quality than the rest of the image. This approach is applicable to images of high and low quality as well as resolution.      

基于直方图匹配的鬼影检测算法

本文研究了背景差方法检测运动目标经常出现的鬼影问题,通过分析前景块边缘区域像素分布,提出了鬼影检测算法。首先,用直方图匹配和平均变化率来衡量前景块边缘区 域的像素分布在当前图像与前帧图像之间的差异;其次,也用直方图匹配来衡量当前图像中前景块边缘区域和与它邻接的背景区域像素分布之间的差别;最后,利用阈值分割割确定直方图匹配极高和平均变化率极小的鬼影块。实验结果表明,本文提出的算法可以快速有效地检测并去除鬼影,同时克服了已有鬼影算法的缺陷。     

积分离散引导的物联网中离散系统差异数据融合

研究一种积分离散引导的物联网中离散系统差异数据融合。对物联网中离散型制造系统下各个物联网节点的差异数据进行融合处理是离散型制造系统需要解决的重要问题。在传统的离散型制造系统中,数据采用分布式处理方法,每个节点的数据做单独处理,所以无法融合所有数据的优点,达到较好的全局效率。提出一种积分离散引导的物联网中离散系统差异数据融合,即采用物联网技术将分布式系统下各个离散制造系统的终端数据进行统一收集和综合,然后采用积分离散引导的方法对获取的所有差异化数据进行处理,从而达到所有数据的有效融合。采用一组100节点的6类型数据进行实验,结果显示,采用积分离散引导的物联网中离散系统差异数据融合,数据被很好地融合起来,且数据的谱平均分布,所以算法具有很好的应用价值。     

Image Restoration in Optical-Acoustic Tomography

We consider the optical-acoustic tomography problem. In the general case, the problem is to reconstruct a real-valued function with a compact support in the n-dimensional Euclidean space via its spherical integrals, i.e., integrals over all (n – 1)-dimensional spheres centered at points on some (n – 1)-dimensional hypersurface. We deal with the cases n = 2 and n = 3, which are of the most practical interest from the standpoint of possible medical applications. We suggest a new effective method of reconstruction, develop restoration algorithms, and investigate the quality of the algorithms for these cases. The main result of the paper is construction of explicit approximate reconstruction formulas; from the mathematical standpoint, these formulas give the parametrix for the optical-acoustic tomography problem. The formulas constructed is a background for the restoration algorithms. We performed mathematical experiments to investigate the quality of the restoration algorithms using the generally accepted tomography quality criteria. The results obtain lead to the general conclusion: the quality of the restoration algorithms developed for optical-acoustic tomography is only slightly lower then the quality of the convolution and back projection algorithm used in Radon tomography, which is a standard de facto.     

Discrete Copulas

We define discrete copulas on a grid of the unit square and show that with each discrete copula there is associated, in a natural way, a bistochastic matrix. This is used in order to introduce the product of discrete copulas. Discrete copulas of order$n$are the smallest convex set containing the irreducible discrete copulas of order$n$introduced by Mayor .     

Discrete optimization

This paper presents some theoretical ideas for the discrete non-linear programming problem. The main objective in to construct a hypercube inside of which the discrete optimum will lie. It is shown that for quadratic functions this hypercube can be constructed by knowing the inverse of the hessian matrix.     

Discrete models in social sciences

Behaviors of solutions of a differential equation and its discretization sometimes differ greatly from each other. For example, even if a differential equation has no chaotic solution, its discretization happens to have a chaotic solution. In this paper, the meanings of this fact in economics are shown. Also, a finite difference model in sociology is given as a chaotic phenomenon.     

Discrete Events in Power Systems

The relevance of Discrete Event System theory (whether synthetic or analytic) to power system analysis and control is not clear. However, based on several characterizations of the domain of discrete systems set forth in the January 1989 Special Issue of the IEEE Proceedings, on Dynamics of discrete event systems (Ho, 1989), we attempt to delineate several power system control problems that may be amenable to analysis by DEDS methodologies. While the author is not qualified to judge whether the latter can speak to any of the examples, it may be relevant that in all cases the problems are non-trivial and in need of further contributions toward improved solutions, especially in view of the ongoing radical restructuring of the industry. The continuous process that is instantiated in the functioning of a power system is observed via three more or less diverse variables. Two of these, the scaler system frequency and the vector system voltage profile, are in principle mensurable physical phenomena; the third, system security, is a quality represented by a set membership conditioned on an inferred relationship between the two physical system variables and future realizations of one or more classes of autonomous stochastic phenomena. (These latter may be internal or external to the physical system, such as, e.g., respectively, equipment failure mechanisms and weather events.)     

离散数学中的DNA计算

由于电子计算机的存贮量小,运算速度慢,智能化低,特别是制造工艺趋于极限。最近,采用计算的可能性引起了人们的广泛关注,尤其是它的良好的并行性。离散数学中的逻辑演算有着广泛的应用,特别是在信息处理方面。论文给出了一个运用图论和DNA计算的方法,解决较复杂的逻辑演算问题。     

Discrete Positive Realness of The Discrete Min-Max Control Law

It is shown that the discrete state dependent min-maxcontroller for an uncertain discrete system with matched uncertainties,is a Discrete Strictly Positive Real (d.s.p.r.) control law.That is to say that an output may always be defined such thatthe nominal open loop is d.s.p.r., and the min-max control lawmay be realized via that output.     

The Euler Characteristics of Discrete Objects and Discrete Quasi-Objects

Assuming planar 4-connectivity and spatial 6-connectivity, we first introduce the curvature indices of the boundary of a discrete object, and, using these indices of points, we define the vertex angles of discrete surfaces as an extension of the chain codes of digital curves. Second, we prove the relation between the number of point indices and the numbers of holes, genus, and cavities of an object. This is the angular Euler characteristic of a discrete object. Third, we define quasi-objects as the connected simplexes. Geometric relations between discrete quasi-objects and discrete objects permit us to define the Euler characteristic for the planar 8-connected, and the spatial 18- and 26-connected objects using these for the planar 4-connected and the spatial 6-connected objects. Our results show that the planar 4-connectivity and the spatial 6-connectivity define the Euler characteristics of point sets in a discrete space. Finally, we develop an algorithm for the computation of these characteristics of discrete objects.     

An Application of Wavelets in Tomography

A method of tomographic inversion using wavelets is described which relies on the “diagonalization” property of wavelets for the derivative of the Hilber transform. Error bounds are given for reconstruction using the technique and an optimal wavelet which minimizes the error is presented. The method is well suited for inversion of from local data.     

离散插值曲面

散乱插值在实际应用中有重要作用.本文通过Vornonoi图构造了一张具有点插值和法向插值的曲面.本文的方法优于目前散乱插值中常用的Shepard方法和三角剖分方法.本文还给出了一种求离散插值曲面的算法,算法的时间复杂性为O(Nlog N),N为散敌点数.