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提升静态小波与自适应PCNN相结合的图像融合算法 总被引:1,自引:0,他引:1
提出了一种新的基于提升静态小波变换与自适应PCNN相结合的图像融合算法.该方法定义一种图像单个像素的清晰度作为PCNN的链接强度,使得PCNN能根据像素清晰度的变化来自适应地调整链接强度的大小,接着对图像经提升静态小波分解得到的低频子带系数的改进拉普拉斯能量和及高频子带系数的单个像素的灰度值,分别作为自适应PCNN神经元的外部输入,并根据点火次数来确定图像融合系数.最后由提升静态小波变换的逆变换得到融合图像.实验表明,该方法在视觉效果和客观评价指标上都优于传统的基于小波变换、提升静态小波变换、提升静态小波-PCNN的图像融合算法. 相似文献
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提出一种基于小波变换的医学超声图像降噪方法。图像进行三次小波分解,对变换后不同尺度的高频子图像进行小波半软阈值处理,最后通过小波逆变换和指数变换重构图像。 相似文献
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根据扫描隧道显微镜(STM)的特点,阐述了将小波变换应用于扫描隧道显微镜的降噪、增强及融合的方法,对于STM扫描获得的石墨原子图像,选用不同的小波基函数和分解层数进行分解和重构,结果表明,利用小波变换对扫描隧道显微镜图像进行处理是有效的、可行的,图像质量得到了明显提高。 相似文献
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基于NSCT和PCNN的红外与可见光图像融合方法 总被引:8,自引:2,他引:6
提出了一种基于非采样Contourlet变换(NSCT)和脉冲耦合神经网络(PCNN)的红外与可见光图像融合方法.首先用NSCT对已配准的源图像进行分解,得到低频子带系数和各带通子带系数;其次对低频子带系数采取一种基于边缘的方法以得到融合图像的低频子带系数;对各带通子带系数提出了一种改进的基于PCNN的图像融合方法来确定融合图像的各带通子带系数;最后经过NSCT逆变换得到融合图像.实验结果表明,本文方法优于Laplaeian方法、小波方法和传统的NSCT方法. 相似文献
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John R. Williams Kevin Amaratunga 《International journal for numerical methods in engineering》1994,37(14):2365-2388
The aim of this paper is to provide an introduction to the subject of wavelet analysis for engineering applications. The paper selects from the recent mathematical literature on wavelets the results necessary to develop wavelet-based numerical algorithms. In particular, we provide extensive details of the derivation of Mallat's transform and Daubechies' wavelet coefficients, since these are fundamental to gaining an insight into the properties of wavelets. The potential benefits of using wavelets are highlighted by presenting results of our research in one- and two-dimensional data analysis and in wavelet solutions of partial differential equations. 相似文献
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为有效识别机械设备中滚动轴承的微弱故障信息,本文提出一种自适应冗余提升小波降噪方法。根据待分解低频尺度系数所含的不同特征,应用范数准则来自适应地选取最匹配于该尺度系数特征的小波函数。同时,引入多孔算法,用以通过冗余性来保证逐层分解后各尺度系数和小波系数所含有的丰富的信息量。接下来,对各层小波系数采用变尺度阈值降噪算法,并对降噪后的系数进行重构及包络谱分析,进而提取滚动轴承的故障特征。应用上述方法分别对轴承实验台轴承混合故障信号和现场实际信号进行分析,均较好地实现了故障识别,验证了本文方法的有效性。 相似文献
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基于半正交B样条小波的任意控制顶点数曲线光顺 总被引:2,自引:0,他引:2
目前,小波分析应用于逆向工程时,对控制顶点有特殊要求,只能处理2j r个控制顶点的图形,为此提出了一种可以光顺任意控制顶点B样条曲线的小波分析新方法。在介绍B样条定义的基础上,从小波分析的定义出发,用严格的数学证明推导了任意控制顶点曲线的小波分解与重构具体算法。最后,该算法成功应用于B样条曲线的小波光顺,实例表明,该算法准确、结果稳定,效率理想。 相似文献
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Recently, considerable amount of attention is being given to the field of wavelets and wavelet packets. It has found numerous
applications in signal representation, image compression and applied mathematics.
In this paper, we present a channel equalization method based on wavelet packets. The proposed equalizer structure is based
on the fact that for sufficiently narrowband sequences, a non-ideal channel can be modelled as an attenuation and delay. If
the data sequence is used to modulate a set of narrowband wavelet packets, then no equalization is required at the receiver
end. The equalization problem reduces to that of determining the delay introduced by the channel for each of the wavelet packets.
A minimum square variance algorithm for adaptively choosing the delay has been proposed. This algorithm has been shown to
perform as desired analytically in a simple delay channel case. Simulations have been used to study its performance in the
non-ideal channel’s case and the results corroborate theoretical predictions. 相似文献
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In this paper we have developed a second generation wavelet based finite element method for solving elliptic PDEs on two dimensional
triangulations using customized operator dependent wavelets. The wavelets derived from a Courant element are tailored in the
second generation framework to decouple some elliptic PDE operators. Starting from a primitive hierarchical basis the wavelets
are lifted (enhanced) to achieve local scale-orthogonality with respect to the operator of the PDE. The lifted wavelets are
used in a Galerkin type discretization of the PDE which result in a block diagonal, sparse multiscale stiffness matrix. The
blocks corresponding to different resolutions are completely decoupled, which makes the implementation of new wavelet finite
element very simple and efficient. The solution is enriched adaptively and incrementally using finer scale wavelets. The new
procedure completely eliminates wastage of resources associated with classical finite element refinement. Finally some numerical
experiments are conducted to analyze the performance of this method. 相似文献
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Kevin Amaratunga Julio Enrique Castrillon‐Candas 《International journal for numerical methods in engineering》2001,52(3):239-271
In this paper, we provide an introduction to wavelet representations for complex surfaces (surface wavelets), with the goal of demonstrating their potential for 3D scientific and engineering computing applications. Surface wavelets were originally developed for representing geometric objects in a multiresolution format in computer graphics. These wavelets share all of the major advantages of conventional wavelets, in that they provide an analysis tool for studying data, functions and operators at different scales. However, unlike conventional wavelets, which are restricted to uniform grids, surface wavelets have the power to perform signal processing operations on complex meshes, such as those encountered in finite element modelling. This motivates the study of surface wavelets as an efficient representation for the modelling and simulation of physical processes. We show how surface wavelets can be applied to partial differential equations, stated either in integral form or in differential form. We analyse and implement the wavelet approach for a model 3D potential problem using a surface wavelet basis with linear interpolating properties. We show both theoretically and experimentally that an O(h) convergence rate, hn being the mesh size, can be obtained by retaining only O((logN) 7/2N) entries in the discrete operator matrix, where N is the number of unknowns. The principles described here may also be extended to volumetric discretizations. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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Yoon Young Kim Gang‐Won Jang 《International journal for numerical methods in engineering》2002,53(7):1575-1592
The objective of the present work is to propose a new adaptive wavelet‐Galerkin method based on the lowest‐order hat interpolation wavelets. The specific application of the present method is made on the one‐dimensional analysis of thin‐walled box beam problems exhibiting rapidly varying local end effects. Higher‐order interpolation wavelets have been used in the wavelet‐collocation setting, but the lowest‐order hat interpolation is applied here first and a hat interpolation wavelet‐based Galerkin method is newly formulated. Unlike existing orthogonal or biorthogonal wavelet‐based Galerkin methods, the present method does not require special treatment in dealing with general boundary conditions. Furthermore, the present method directly works with nodal values and does not require special formula for the evaluation of system matrices. Though interpolation wavelets do not have any vanishing moment, an adaptive scheme based on multi‐resolution approximations is possible and a preconditioned conjugate gradient method can be used to enhance numerical efficiency. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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Jian‐Gang Han Wei‐Xin Ren Yih Huang 《International journal for numerical methods in engineering》2006,66(1):166-190
The wavelet‐based methods are powerful to analyse the field problems with changes in gradients and singularities due to the excellent multi‐resolution properties of wavelet functions. Wavelet‐based finite elements are often constructed in the wavelet space where field displacements are expressed as a product of wavelet functions and wavelet coefficients. When a complex structural problem is analysed, the interface between different elements and boundary conditions cannot be easily treated as in the case of conventional finite‐element methods (FEMs). A new wavelet‐based FEM in structural mechanics is proposed in the paper by using the spline wavelets, in which the formulation is developed in a similar way of conventional displacement‐based FEM. The spline wavelet functions are used as the element displacement interpolation functions and the shape functions are expressed by wavelets. The detailed formulations of typical spline wavelet elements such as plane beam element, in‐plane triangular element, in‐plane rectangular element, tetrahedral solid element, and hexahedral solid element are derived. The numerical examples have illustrated that the proposed spline wavelet finite‐element formulation achieves a high numerical accuracy and fast convergence rate. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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一种紧支集双正交小波基的构造 总被引:7,自引:0,他引:7
基于对偶尺度函数及对偶小波,提出了一种构造紧支集双正交小波基的算法,并给出严密的证明和推导过程。应用该算法,结合函数优化方法,构造出一系列包括样条小波、接近正交的双正交小波及其它具有特殊性质的双正交小波。该构造算法丰富了小波理论,可以广泛应用于信号分析、图像处理等领域。 相似文献