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理论上,讲在DCT域的DC系数嵌入水印有更好的鲁棒性,而有意义二值图像的优点在于意义直观的。在此提出了一种DCT域的有意义二值图像水印嵌入和检测、提取算法。用二值水印图像调制伪随机序列生产水印序列,将宿主图像分块并分类,水印嵌入到DCT域的DC系数。仿真试验了嵌入、攻击和提取过程,表明该算法嵌入的水印有比较好的鲁棒性和不可见性。 相似文献
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为改进基于脆弱数字水印的多媒体数据认证的性能,利用逆问题的扰动现象提出了一种新的脆弱水印体制.在新的方法中,数据完整性或签名的验证并不依赖于水印的提取,而通过反向求解植入方程完成.由于扰动现象的存在,在数据被篡改的情况下,反向求得的数据值将产生猛烈的增长,并且,扰动值反映了篡改的程度,扰动区域正好描述了篡改的轮廓.在这一机制下,脆弱水印还可以引入自适应植入算法,在被保护数据的每一码字上植入水印.与常用的基于分块的算法相比,所提出的算法在提高篡改敏感性和可定位性的同时,还兼顾了感知透明性. 相似文献
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空间域与频率域相结合的抗图像处理全息水印 总被引:3,自引:3,他引:0
为了解决数字全息水印技术无法抵抗图像处理攻 击的问题,采用共轭对称延拓生成低噪声加密全息水印图像, 嵌入水印时采用频率域的离散余弦变换(DCT)与空间域的拉普拉斯金字塔变换方法相结合。 首先,对水印图像进行傅立叶共轭对称 延拓生成低噪声的双随机加密全息水印,对宿主图像进行拉普拉斯金字塔分解,提取拉普拉 斯金字塔第1层残差图像;然后, 通过DCT,将加密水印替换其中高频域后逆DCT;最后,嵌入水印信息后的第1层拉 普拉斯残差图像与其他残差 图像重构成含水印图像。实验结果表明,含水印图像的峰值信噪比(PSNR)值达到35.7dB,细节损失少,提取水印图像人眼可清 晰分辨水印内容,且在满足不可见性的同时可以抵抗常见的图像处理攻击,保 证了水印信息鲁棒性与安全性的 要求,能够应用于实际生产中。 相似文献
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提出了一种基于时域变换的、隐藏效果良好的、具有鲁捧性的数字水印算法。由此产生的已嵌入水印的目标图无噪声现象,有良好的视觉质量和理想的PSNR。加入水印的目标图经过各种处理(特别是JPEG压缩、划痕和剪切)后所提取的水印依然是可识别的。 相似文献
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电镀后板面水印问题的研究及解决 总被引:1,自引:1,他引:0
1 前言 PTH、电镀后板面水印现象一直是一个棘手的问题,夏季尤为突出。所谓水印,并非电镀后板面因水迹印氧化后的视觉效果,而是表现出的镀铜凹凸不平,其轮廓恰似水在版面上溅滴或流动过后留下的痕迹,故又称水印凹痕。水印凹痕根据其严重程度不同其铜厚大约比正常镀铜厚度薄20%~60%。既会影响其后干膜的粘 相似文献
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针对嵌入的水印信息与宿主信息存在一定关联性,深入研究了音频水印的盲检测方案,通过设定不同的假设条件,分析了其对应的盲水印检测过程.首先介绍了音频水印算法的嵌入过程和水印盲检测原理,然后深入分析了音频水印盲检测过程中水印信息与宿主信息之间的关联性,并分别以半盲检测算法和盲检测算法为代表,分析了水印信息与宿主信息之间的关联性,并得出了量化的计算式. 相似文献
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基于小波变换的双水印算法 总被引:2,自引:0,他引:2
数字音频水印是水印技术中重要的组成部分。而近年来对音频水印的研究远远少于图像水印,双水印的研究则更加少。因此提出了一种基于小波变换的双水印算法,在音频信号的小波变换域嵌入两个不同作用的水印,对一些音频处理有很好的鲁棒性的同时又能有效地判别音频信号的真实性和完整性。实验证明本算法的两水印分别具有很好的鲁棒性和敏感性,并实现了水印的盲提取。 相似文献
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The optimization problem of rearrangeable multihop lightwave networks is considered. The authors formulate the flow and wavelength assignment problem, when minimizing the maximum flow in the network, as a mixed integer optimization problem subject to linear constraints. The problem is decomposed into two independent subproblems, the wavelength assignment (or connectivity problem) and the flow assignment (or routing problem). A simple heuristic provides a meaningful formulation to the connectivity problem, in a form similar to a transportation problem. An algorithm is then proposed which finds a heuristic initial logical connectivity diagram and the corresponding routing, and then iterates from that solution by applying branch-exchange operations to the connectivity diagram. The algorithm was tested on illustrative traffic matrices for an 8 node network with two transmitters and two receivers per node, and an improvement in achievable throughput over the Perfect Shuffle interconnection pattern was shown in all cases 相似文献
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Assignment of cells to switches in PCS networks 总被引:1,自引:0,他引:1
《Networking, IEEE/ACM Transactions on》1995,3(5):521-526
Considers a problem of network design of personal communication services (PCS). The problem is to assign cells to the switches of a PCS network in an optimum manner. The authors consider two types of costs. One is the cost of handoffs between cells. The other is the cost of cabling (or trunking) between a cell site and its associated switch. The problem is constrained by the call volume that each switch can handle. The authors formulate the problem exactly as an integer programming problem. They also propose a heuristic solution for this problem and show that it performs extremely well 相似文献
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M. Yu. Medvedik Yu. G. Smirnov 《Journal of Communications Technology and Electronics》2011,56(8):947-952
The problem of diffraction of an external electromagnetic field by a locally inhomogeneous body placed in a rectangular waveguide
with perfectly conducting walls is considered. The formulated problem is reduced to a volume singular integral equation. The
problem is solved with the use of the numerical collocation method. A subhierarchical method is applied to analyze the problem
for structures of a complex geometric shape. Because of a large amount of computation, the problem is solved with the use
of parallel algorithms realized on a supercomputer complex. 相似文献
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引入D2D通信的蜂窝网上行资源分配算法 总被引:1,自引:0,他引:1
该文研究了引入Device-to-Device (D2D)通信的蜂窝网系统中的上行资源分配问题。首先将该问题建模为一个简洁的二值整数规划问题。然而整数规划仍是NP难问题。该文利用Canonical对偶理论,得到其对偶形式。该对偶问题是一个连续域内的凸问题。证明了在特定的条件下,可以通过求解对偶问题得到原问题的最优解,且对偶间隙为零。提出了一个基于Barrier方法的算法来求解对偶问题。仿真结果表明,该文的算法优于现有算法,且性能接近最优。 相似文献
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Vo B. Zang Z. Cantoni A. Teo K.L. 《Vision, Image and Signal Processing, IEE Proceedings -》1995,142(6):389-394
The envelope constrained (EC) filtering problem is concerned with designing a filter which minimises the gain to input noise while its response to a given signal fits into a prescribed envelope. This problem had been formulated as a constrained optimisation problem in Hilbert space. By restricting these filters to the span of a finite orthonormal set, the EC filtering problem can be posed as a finite dimensional optimisation problem with a continuum of constraints. The constrained problem is approximated by an unconstrained problem which is then solved by descent direction based algorithms. It is shown that these algorithms converge globally, and one in particular has a quadratic rate of convergence. Numerical examples using the orthonormal Laguerre series approximation are studied 相似文献
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分析了基于问题的创新性研究和研究性教学的内涵,特别强调了如何提出科学问题的重要性以及应遵循的需求牵引、问题驱动和问题求解的科学研究特征。并且以信息化和网络化环境下多飞行器协同作战为实例,分析了多飞行器网络化协同控制的需求和特点,进而详细论述了如何分析问题和提出问题的详细过程,并说明了不同学科知识交叉和融合应用的重要性,便于领会如何在实际中提出问题并开展基于问题的创新性研究和研究性教学。 相似文献
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Sami J. Habib 《International Journal of Communication Systems》2007,20(2):159-176
This paper describes a capacity planning tool NETCAP, which is a prototype software program for automatically planning and integrating application‐specific content‐distribution networks (CDNs). The CDN integration problem consists of two problems: data management system design problem and network topology design problem. The data management system design problem comprises of the server placement and file allocation problems, where the network topology design problem involves determining the network topology with network technology considerations. The CDN integration problem has been formulated as an optimization problem; where the objective function is to optimize a network topology that satisfies both the servers' access requirements and clients' communications. An evolutionary technique is used in NETCAP to search the design space. The experimental results for a CDN integration problem described here demonstrate the effectiveness of NETCAP in finding good CDN designs from a large design space in a few minutes. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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The delay-aware dynamic resource management problem was investigated in sensor network,with a focus on resource allocation among the sensors and power control along the time.By taking account of average delay requirements and power constraints,the considered problem was formulated into a stochastic optimization problem.Inspired by Lyapunov optimization theory,the intractable stochastic optimization problem was transformed into a tractable deterministic optimization problem,which was a mixed-integer resource management problem.By exploiting the specific problem structure,the mixed-integer resource management problem was equivalently transformed into a single variable problem,and the cooperative distributed method was present to effectively solve it with guaranteed global optimality.Finally,a dynamic resource management algorithm was proposed to solve the original stochastic optimization problem.Simulation results show the performance of the proposed dynamic algorithm and reveal that there exists a fundamental tradeoff between delay requirements and power consumption. 相似文献
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Eriko Tokuda Noboru Asahi Takashi Yamada Yoshihito Amemiya 《Analog Integrated Circuits and Signal Processing》2000,24(1):41-49
Analog computation is a processing method that solves a given problem by utilizing an analogy of a physical system to the problem. An idea is presented here for relating the behavior of single-electron circuits to analog computation. As an instance, a method is proposed for solving a combinatorial problem, the three-colorability problem, by using the properties of single-electron circuits. In problem solving, a single-electron circuit is constructed that is analogous to a given problem; then, through an annealing procedure, the circuit is made to settle down to its minimun energy state. The correct solution to the problem can be obtained by checking the final arrangement of electrons in the circuit. Analog computation is a promising architecture for single-electron computing systems. 相似文献