共查询到20条相似文献,搜索用时 921 毫秒
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为了与图像压缩标准JPEG2000相适应,提出了两种可直接在JPEG2000压缩域内进行信息隐藏的方法,分别采用JPEG2000编码过程和解码过程进行实现。它们既支持无损压缩,也适用于有损压缩,从而具有较广的适用范围。实验结果表明这两种实现方法具有较好的不可见性和压缩性。 相似文献
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JPEG2000中可逆颜色变换探讨 总被引:1,自引:0,他引:1
为了实现彩色图像的完全可逆压缩,通过分析目前彩色图像压缩需要进行色彩空间转换的必要性,并在JPEG压缩标准的可逆颜色空间转换研究的基础上,指出了JPEG2000压缩标准中可逆颜色空间转换公式中所存在的一些问题。文中主要对JPEG2000中颜色空间I0I1I2和Y0Y1Y2的可逆变换,利用提升的方法给出了从整数到整数的完全可逆变换过程。从而为JPEG2000压缩标准中完全可逆图像压缩中色彩空间转换提供了一种简单而有效的实现方法。 相似文献
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提出了一种基于JPEG2000的图象局部可分级检索方法。首先,对图象采用JPEG2000的基本算法进行压缩编码;然后,把压缩码流按零树结构编排,每个零树结构对应着图象的某个网格区域,从零树结构所包含的DWT系数可以分级重建这个网格区域的内容。检索时,先从图象的最低分辨率子图象(即LL子图象)的预览开始,一旦发现目标,则锁定目标;然后在空间分辨率和信噪比两个方面逐级浮现目标所在网格的内容。由于该方法仅仅使用部分压缩码流数据来恢复图象的局部内容,从而节省了大量的计算资源;最后给出了基于JPEG2000的图象局部可分级检索的实验实例。 相似文献
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JPEG2000中不同小波基的图像压缩性能分析 总被引:6,自引:0,他引:6
主要讨论了用JPEG2000标准进行静态图像压缩时,小波基的选择对图像压缩性能的影响.我们根据JPEG2000标准,比较了各类图像在不同小波基下的压缩结果,发现在JPEG2000中,小波基的选择在一定程度上影响了图像的压缩性能.对于某些图像,JPEG2000标准的缺省小波基并不能取得较优的压缩结果.文中分析了影响图像压缩性能的小波基与图像的特性,在此基础上,给出JPEG2000进行图像压缩时小波基的选择方法. 相似文献
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JPEG2000图像压缩算法概述及网络应用前景 总被引:3,自引:0,他引:3
概述了JPEG2000图像编码系统,通过图例详细分析了JPEG2000的图像压缩编码过程,最后论述了JPEG2000的网络应用前景。 相似文献
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为了实现彩色图像的完全可逆压缩,通过分析目前彩色图像压缩需要进行色彩空间转换的必要性,并在JPEG压缩标准的可逆颜色空间转换研究的基础上,指出了JPEG2000压缩标准中可逆颜色空间转换公式中所存在的一些问题。文中主要对JPEG2000中颜色空间I0I1I2和Y0Y1Y2的可逆变换,利用提升的方法给出了从整数到整数的完全可逆变换过程。从而为JPEG2000压缩标准中完全可逆图像压缩中色彩空间转换提供了一种简单而有效的实现方法。 相似文献
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JPEG2000标准是最新的图像压缩标准.首先分析了JPEG2000标准中的抗误码方法,进而提出了一个分析模型来预测在无线信道上传输的JPEG2000编码图像重建质量,并通过仿真加以验证.此分析模型可用来在无线基站上为JPEG2000编码图像的传输设计高效的非均匀误码保护方案.基于该分析模型,定义了一个效用函数来在图像重建质量和传输开销之间进行折中。以决定采用何种非均匀误码保护方案。达到最佳的传输质量. 相似文献
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基于内容的检索是近年来的研究热点之一,现在已有许多基于象素域的图像检索技术,目前数据压缩也已成为多媒体应用的标准模式,静态图像压缩主要采用JPEG技术,研究基于传统JPEG和JPEG2000的图像检索方法成为必然。本文综述近年来出现的基于JPEG核心算法离散余弦变换和JPEG2000核心算法离散小波变换的图像检索技术。 相似文献
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交通流量预测是智能交通系统的核心内容,系统中多个功能的实现都是以其为基础。针对城市路网中交通流量的时域性以及准周期特性,提出了一种基于改进小波神经网路算法的交通流量预测方法。利用具有时域分辨能力的小波神经网络对流量信号进行分类,以实现对交通流量的预测;采用加动量项的方法对网络权值及参数进行修正,避免了神经网络训练时收敛缓慢以及陷入局部极小。通过仿真实验验证,提出方法可实现对交通流量的准确预测,并且可以有效地提高网络学习率。 相似文献
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针对分散控制无法实现子系统之间的信息交换,将分布式控制应用于网络化系统,以期实现子系统之间的信息交换和提高网络的性能.利用Lyapunov函数法,分别给出了在传统分散控制和网络分布式控制下的整个网络化系统稳定性的判据;给出了可容许的最大时滞的优化算法.将所得到的理论结果,结合到一个简单的网络化系统,进行数值仿真.结果表明,与传统分散控制相比较,网络分布式控制更能提高整个网络化系统稳定性的收敛速度. 相似文献
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A new approach to speed control of induction motors is developed by introducing networked control systems (NCSs) into the induction motor driving system. The control strategy is to stabilize and track the rotor speed of the induction motor when the network time delay occurs in the transport medium of network data. First, a feedback linearization method is used to achieve input-output linearization and decoupling control of the induction motor driving system based on rotor flux model, and then the characteristic of network data is analyzed in terms of the inherent network time delay. A networked control model of an induction motor is established. The sufficient condition of asymptotic stability for the networked induction motor driving system is given, and the state feedback controller is obtained by solving the linear matrix inequalities (LMIs). Simulation results verify the efficiency of the proposed scheme. 相似文献
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Networked model predictive control based on neighbourhood optimization for serially connected large-scale processes 总被引:1,自引:1,他引:1
In this paper, two novel networked model predictive control schemes based on neighbourhood optimization are presented for on-line optimization and control of a class of serially connected processes (known as the cascade processes in some references), in which the on-line optimization of the whole system is decomposed into that of several small-scale subsystems in distributed structures. Under network environment, the connectivity of the communication network is assumed to be sufficient for each subsystem to exchange information with its neighbour subsystems. An iterative algorithm for networked MPC and a networked MPC algorithm with one-step delay communication are developed according to different network capacities. The optimality of the iteration based networked MPC algorithm is analyzed and the nominal stability is derived for unconstrained distributed control systems. The nominal stability with one-step delay communication is employed for distributed control systems without the inequality constraints. Finally, an illustrative example and the simulation study of the fuel feed flow control for the walking beam reheating furnace are provided to test the effectiveness and practicality of the proposed networked MPC algorithms. 相似文献
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Guaranteed Cost Control of Networked Control Systems Under Transmission Control Protocol with Active Queue Management
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The problem of a guaranteed cost controller design of networked control systems under transmission control protocol (TCP) is derived. To improve the overall performance of the networked control system, a scheme to simultaneously control the plant and the network is presented. An analytical TCP model is used to design active queue management (AQM) to achieve the desired queue length, which is helpful in reducing the variation of the network induced delay. Moreover, a new closed loop model of networked control systems is obtained by augmenting the TCP communication model with the control plant. The guaranteed cost controller is addressed in terms of a linear matrix inequality (LMI) to render the system asymptotically stable based on Lyapunov‐Krasovskii theory and weighted technology. Finally, numerical simulations are included to demonstrate the theoretical results. 相似文献
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This paper presents a procedure for studying impulsive synchronization motion in networked open-loop multibody systems formulated by Lagrange dynamics. Impulsive motion occurs when the networked systems are physically subject to either direct or indirect impulsive effects, or when subjected to both simultaneously. The impulsive effects are usually caused by impulsive forces or impulsive constraints. The governing equations of networked open-loop multibody systems are developed from Lagrange formulation. The procedure automatically incorporates a preliminary feedback control and the effects of impulsive constraints through its analysis. Some generic criteria on exponential synchronization of the system output with respect to generalized coordinates and its velocities over, respectively, undirected fixed and switching network topologies, are derived analytically. The procedure shows that impulsive synchronization motion in networked open-loop multibody systems can achieve by impulsive constraints strategies. Two examples and simulations are used to demonstrate and validate the analysis procedure. 相似文献
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针对如何保证精确的分布式时钟同步以实现预期的实时调度和控制问题,通过对一类基于全双工交换式以太网并采用总线型拓扑的网络化控制系统时延特征的分析,结合网络精确时钟同步协议,在分析了其可行性的基础上,给出了网络化控制系统时钟同步的设计及实现方法. 相似文献
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从网络计算理论、网络科学和网络设计、网络设计与工程、网络设计与社会价值等方面阐述了构建未来网络面临的若干问题,其中任何一个问题的解决都将极大地推动计算机网络的发展。 相似文献
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Shen Chunshan Shen Fei Wu Zhongcheng Luo Jiarong 《Computer Standards & Interfaces》2009,31(2):454-457
Network of measurement and control is now converging with network of information tightly more and more, which improves the development of network-distributed measurement and control technology. And networked sensors are important unit in networked measurement and control system. This paper applied Session Initiation Protocol (SIP) to networked sensors system aimed for a kind of unified IEEE 1451 NCAP model of networked sensors using SIP as the interface. We analyzed the features of SIP and sensor network interface, presented a frame of networked sensor based on SIP according to IEEE1451 sensor standards, and studied on-line register of networked sensor based on SIP. Devices supported by SIP in distributed control system can communicate easily with IP-based information network, and can also provide conveniently multimedia service. SIP and P2P SIP are worthy of deep research for networked sensor system. 相似文献