共查询到20条相似文献，搜索用时 312 毫秒
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高空间分辨率太阳图像中的列固定模式噪声降低了图像质量并对太阳大气现象、太阳物理的研究产生了影响。针对传统小波变换处理列固定模式噪声不足的问题,提出一种新型的基于小波变换和双滤波的去噪算法。首先,根据噪声的产生机理以及存在形式,将原始图像对数化并进行小波变换。其次,对小波域中的垂直分量进行中值滤波,去除其中的噪声小波系数。再次,利用小波逆变换得到无噪图像,并与对数化图像做差提取初始噪声。然后,对初始噪声进行低通高斯滤波并指数化得到结果噪声。最后,用原始图像除以结果噪声便得到去噪后的图像。真实图像的实验结果表明本文算法的去噪效果优于其他算法。实验表明本文算法在去除列固定模式噪声的同时,能够很好的保留图像信号,提高图像质量。 相似文献
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《科技通报》2015,(12)
针对传统单小波在对称性、正交性、有限支撑等特性上的不足,提出一种基于多小波分析的图像优化去噪方法。对图像进行预滤波处理操作,消除多小波的不恰当离散性。对待处理信号经预滤波处理后产生的四个分量进行多小波变换处理。采用Visu shrink方法与基于stein无风险估计的Sureshrink方法对阈值进行确定。保持总像素量不变,给出多小波分解及重构系统框图。以S=2的多小波为例对多小波变换进行分析。分别完成行滤波和列滤波。对噪声方差进行预测,完成对原始图像多小波系数的方差的估计,对尺度参数和阈值进行计算。仿真实验结果表明,所提方法能够有效去除图像噪声,进一步增强了图像的信噪比。 相似文献
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斑点噪声是SAR图像的本质特征,是机理性的,在很大程度上影响了对图像的理解和判读。到目前为止,对SAR图像进行降斑的方法多数要用到斑点噪声的统计特性,一般SAR用户使用起来较困难。因此可以针对SAR图像斑点噪声的特点,利用基于传统空域滤波的方法,通过加权图像融合,得到斑点改善的SAR图像,可以满足一般用户的使用要求。 相似文献
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瞬变电磁法是当前煤矿电法勘探中最常用的物探方法之一。在瞬变电磁数据采集时,不可避免地受到各种噪声的干扰,传统的去噪方法已不能适应目前的勘探精度要求。通过对一维信号模型加入高斯白噪声进行小波去噪计算机仿真,结果表明小波变换去除高频噪声效果良好。实测资料数据处理结果表明,选择合适的小波簇进行小波分析能有效地区分有用信号与干扰噪声,是一种瞬变电磁信号去噪的可行实用的方法, 相似文献
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钻井模拟中的测井信号往往存在着与地层无关的噪声干扰,必须进行去噪处理。小波变换可以滤除测井信号的噪声和干扰,但其去噪效果与阈值的选取有关。本文从理论上介绍了阈值的选取准则及阈值选取方法,再从实验角度对四种阈值选取方法（Stein无偏似然估计阈值法、固定阈值法、混合型阈值法和最小最大准则阈值法）进行了分析计算,最终选定混合型阈值小波消噪法去除测井信号的噪声。对实际测井信号的处理效果表明,混合型阈值小波消噪法不仅去噪效果好,而且较好的保留了测井信号的分辨率,适用于测井信号的去噪。 相似文献
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图像在形成、传输、存储过程中,不可避免地会受到各种噪声的干扰,极大地影响了人们从图像中提取信息,因此,采用适当的方法尽量减少图像噪声是一个十分重要的处理步骤。小波变换应用于图像去噪领域比较成功,在图像去噪中能更好地保护图像细节。本文提出了一种多个小波基联合去噪的方法,该方法能够很好的去除图像中常见的噪声。 相似文献
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文章针对基于Matlab的数学图像处理环境,对其结构、特点及应用做了介绍,重点阐述了Matlab基于形态学数字图像处理的问题,并将形态滤波器与传统滤波器进行了比较。 相似文献
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提出了一种基于经验模式分解去斑和顶帽变换背景不均匀的预处理方法. 经验模式分解去斑算法先对图像每一列进行经验模式分解得到IMF函数,然后将原信号与第一、二模态相减得到初步处理图像,再对该图像每一行重复该操作从而得到去斑图像,该算法有效地去除斑点噪声;顶帽变换则有效地补偿了海浪带来的局部不均匀的背景亮度,提高了图像的信杂比,有利于目标的检测. 仿真结果证明了算法的有效性. 相似文献
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针对传统多带宽合成孔径雷达系统需要多个滤波器和多种采样时钟等问题,提出一种新的数字处理方法,并详细介绍了算法方案、仿真结果和基于现场可编程门阵列(FPGA)的算法实现.该方法仅需一个最高频率的采样时钟获取离散化数据,通过对数据的插值得到其他较低时钟频率的数据,而对不同带宽信号的滤波由数字滤波器来实现.这种方法简化了系统设计,提高了系统可靠性. 相似文献
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A new transitional filter based on the sum of filter polynomials is proposed and discussed. It shall be shown that the approach allows for greater flexibility in adjusting passband and stopband gain shapes. The sensitivity of the filter transfer function is analyzed and related to the approximation problem. Some new modified classical filters are also derived including maximally flat (Butterworth) and equiripple (Chebyshev) types. Several examples of combining Butterworth, Chebyshev and sync-tuned filters are presented and compared to those obtained using the conventional product method. The new transitional filter provides an alternative to other forms and provides a means for isolating the effects of non-uniformly distributed pole angles. 相似文献
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A new design method based on artificial bee colony algorithm for digital IIR filters 总被引：11，自引：0，他引：11
Nurhan Karaboga Author Vitae 《Journal of The Franklin Institute》2009,346(4):328-348
Digital filters can be broadly classified into two groups: recursive (infinite impulse response (IIR)) and non-recursive (finite impulse response (FIR)). An IIR filter can provide a much better performance than the FIR filter having the same number of coefficients. However, IIR filters might have a multi-modal error surface. Therefore, a reliable design method proposed for IIR filters must be based on a global search procedure. Artificial bee colony (ABC) algorithm has been recently introduced for global optimization. The ABC algorithm simulating the intelligent foraging behaviour of honey bee swarm is a simple, robust, and very flexible algorithm. In this work, a new method based on ABC algorithm for designing digital IIR filters is described and its performance is compared with that of a conventional optimization algorithm (LSQ-nonlin) and particle swarm optimization (PSO) algorithm. 相似文献
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《Information processing & management》2022,59(1):102726
In synthetic aperture radar (SAR) image change detection, the deep learning has attracted increasingly more attention because the difference images (DIs) of traditional unsupervised technology are vulnerable to speckle noise. However, most of the existing deep networks do not constrain the distributional characteristics of the hidden space, which may affect the feature representation performance. This paper proposes a variational autoencoder (VAE) network with the siamese structure to detect changes in SAR images. The VAE encodes the input as a probability distribution in the hidden space to obtain regular hidden layer features with a good representation ability. Furthermore, subnetworks with the same parameters and structure can extract the spatial consistency features of the original image, which is conducive to the subsequent classification. The proposed method includes three main steps. First, the training samples are selected based on the false labels generated by a clustering algorithm. Then, we train the proposed model with the semisupervised learning strategy, including unsupervised feature learning and supervised network fine-tuning. Finally, input the original data instead of the DIs in the trained network to obtain the change detection results. The experimental results on four real SAR datasets show the effectiveness and robustness of the proposed method. 相似文献
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把通常用于图像处理的CLEAN算法引入到SAR成像处理中,提出一种基于CLEAN 的SAR图像旁瓣抑制方法.分析算法流程,比较点目标仿真结果和RADARSAT-1海洋稀疏目标场景成像结果,表明该方法在保证成像分辨率的同时,能够有效地抑制合成孔径雷达图像的旁瓣. 相似文献
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一种规整化的各向异性扩散相干斑抑制算法 总被引：2，自引：0，他引：2
针对基于各向异性扩散的相干斑抑制算法 (SRAD)中存在的不合理性 ,即算法在均匀区域内降噪特性一般 ,并且扩散系数的非凸可能导致解不收敛到正确的图像 ,从理论上进行了系统的分析和论证 ,并依据保持图像细节的规整化准则 ,构造出新的扩散控制系数 .在此基础上 ,进一步提出了一种更合理的规整化各向异性扩散模型 (RSRAD) ,该模型可以有效地克服SRAD中存在的不合理性 .实验结果表明 ,RSRAD算法优于SRAD . 相似文献
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The construction of nomographs for transitional classical filters is described. Gain functions of classical filters are related to filter requirements resulting in a formulation for the general gain nomograph. The transitional filters that are products of approximating polynomials are incorporated into the general gain nomograph resulting in transitional filter nomographs that are sums of the individual nomographs. Nomographs for transitional filters using alternative forms where poles are interpolated are also considered. The resulting nomographs allow for quick optimization of transitional filter frequency response in many cases. Design examples are submitted and discussed. The proposed transitional filter nomographs provide the engineer with increased insight into the selection of classical transitional filters with optimum frequency response. 相似文献