共查询到19条相似文献，搜索用时 109 毫秒
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有效地抑制或消除斑点噪声是SAR图像地学应用的前提，通过基于单视数SAR图像的Speckle统计特性和已发展的空间滤波算法分析。发展了一种改进的全方向动态窗口自适应SAR噪声滤波算法，该算法对处理的每一个像元可按图像边界细节划分为需要的全方向子窗口，利用相对标准差判断滤波窗口及子窗口内斑点噪声及边缘信息的存在情况，可实现滤波窗口大小动态调整和窗口内参加滤波像素的自适应选择，对ERS SAR SLC图像试验结果表明，该算法对单视数SAR图像具有较强的Speckle抑制能力。且可较好地保持图像的纹理边界细节信息，有一定的实用价值。 相似文献
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单视数SAR图像Speckle滤波方法的研究 总被引：5，自引：0，他引：5
在分析单视数ＳＡＲ像的Ｓｐｅｃｋｌｅ局部统计特性和现有的空间滤波算法的基础上,提出上,提出了一种新的Ｓｐｅｃｋｌｅ滤波方法,该方法采用特殊的滤波窗口邻域划分方法,根据窗口相对标准差自适应地调整窗口设计的窗口内的滤波区域。 相似文献
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提出了一种新的斑点噪声的滤波方法，该方法基于小波分解的框架，采用小波域隐MRF模型，计算图像中表征像素纹理特征的隐状态参数的后验概率，以此后验概率作为权重因子对传统GammaMAP滤波算法进行改进。该算法被用于模拟SAR图像和真实ERS-1图像的Speckle抑制。试验结果表明，与传统Gam—maMAP算法相比，本文提出的方法能更好地抑制Speckle，并保持图像细节。 相似文献
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一种基于小波分析的SAR图像斑点噪声滤波算法 总被引：5，自引：0，他引：5
利用多分辨率小波分析的理论，分析了SAR图像经多分辨率小波分解后生成的系列子图像中信号与斑点噪声能量分布特性及其信噪比的变化规律，提出了一种新的小波域斑点噪声的滤波算法，该滤波算法阈值取决于各细节子图像的序列长度、方差及其所在的层次，并采用真空SAR数据和模拟加噪图像进行了试验。 结果表明，该算法具有较强的噪声抑制和较好的边缘、细节保护能力及目视效果。 相似文献
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合成孔径雷达(Synthetic Aperture Radar, SAR)成像过程中会出现斑点噪声,一般用多视处理减少图像的斑点噪声,这对合成孔径雷达船只探测造成了一定的影响.本文对不同视数SAR图像的等效视数、空间分辨率和船只海面对比度进行了分析,结果表明:一方面,多视处理增加了等效视数,改善了图像质量,更有利于船只探测;但另一方面,多视处理又降低了图像空间分辨率和船只海面对比度,对船只探测产生不利影响.最后本文选取了窗口滤波法和K分布法两种典型的SAR船只探测方法对多视处理的SIR-C SAR图像进行了船只探测试验,得到了最适合船只探测的多视处理的视数. 相似文献
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极化SAR图像自适应增强Lee滤波算法 总被引：1，自引：0，他引：1
精制极化Lee滤波算法以其简单、高效、健壮等优点在极化SAR图像处理解译中得到了广泛的应用。然而,此滤波算法存在明显的缺陷：扇贝效应和虚假细线。对此,本文提出增加一组均匀窗口及一组线性方向窗口,并采用大小自适应窗口机制,在同质度高的区域用大窗口滤波,在同质度低的区域用小窗口滤波,从而使得滤波窗口在形状和尺寸上都能自动适应实际场景。利用机载和星载全极化SAR数据进行的滤波实验结果表明,本文提出的自适应增强Lee滤波算法在同质区域的噪声抑制能力明显优于精制极化Lee滤波算法及改进的Sigma滤波算法,同时在保持点、线等细节信息方面也优于精制极化Lee滤波算法,并且能很好的保持图像中地物的极化散射信息。 相似文献
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在分析四分量极化散射理论基础上,提出了一种新的极化SAR数据相干斑滤波算法。该算法首先应用四分量散射模型对原始极化SAR数据进行分解,以获得像素的散射类型和总功率值;然后采用极化特征和空间特征的相似性度量,在滤波窗口内选取中心像素的同质区;最后根据同质区的局部统计特性,应用线性最小均方滤波器进行滤波处理。AIRSAR系统L波段极化SAR数据的实验结果表明,该算法不仅可有效抑制相干斑,而且对极化和边缘等细节信息也有较好的保持。 相似文献
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InSAR相位干涉图滤波方法研究 总被引：2，自引：0，他引：2
合成孔径雷达干涉测量(InSAR)中相位干涉图的质量是决定干涉测量精度的关键因素之一。在其他影响因素确定的情况下,干涉图滤波是提高干涉图质量的有效手段。介绍多视数均值滤波与基于梯度的自适应滤波,分析其优缺点,在此基础上,探讨这两种滤波相结合的综合滤波方案,提出直接对InSAR相位干涉图的实部和虚部进行综合滤波的方法,给出具体流程图。最后,通过对实际SAR数据的处理验证所提出的滤波方法抑噪效果明显,且能很好地保持相位干涉图的边缘信息。 相似文献
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Sahel Mahdavi Bahram Salehi Cecilia Moloney Weimin Huang Brian Brisco 《International Journal of Digital Earth》2018,11(7):703-729
Speckle degrades the radiometric quality of a Synthetic Aperture Radar (SAR) image. Previous methods for speckle reduction have used a fixed-size window for filtering the entire image. This, however, may not be effective for the entire image, as land covers of different sizes require different filtering windows. In this paper, a novel method is proposed by which each pixel in the image is filtered with a window appropriate for the size of object within it. The real in-phase and the imaginary quadrature components of the SAR images determine the best window size and the pixels in the intensity image are filtered using their own optimal windows. The proposed method is presented for both single- and multi-polarized SAR images, and the results of several common filters that were modified are presented. This approach is applied to two RADARSAT-2 images: one over San Francisco, California, USA and the other over St. John’s, Newfoundland and Labrador, Canada, producing results that were similar to, or outperformed, comparable filters while retaining details and suppressing speckle effectively. While the method was successful for single-look intensity data, it offers great potential for multi-look and amplitude data as well. 相似文献
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由于现有边缘检测方法多存在对图像噪声的敏感性以及检测边缘的有限方向性等问题,因此在斑点噪声的影响下难以有效检测SAR图像中具有任意方向性且强度相近的区域间边缘。本文提出了一种任意方向对称窗口的SAR图像边缘提取算法。首先,以任意像素在图像中的格点位置为对称中心构建任意方向上的对称窗口;定义各窗口内像素到中心像素距离的核函数;以像素核函数为权重分别计算两对称窗口内像素光谱测度的加权平均值,并定义两者之差的绝对值为该方向上该像素隶属边缘的强度;选取所有方向中最大边缘强度作为边缘像素的判别标准。为去除错误提取的边缘像素,设计基于滤波操作的后处理过程。对模拟图像提取结果的定性及定量分析表明提出算法可在一定程度上克服噪声影响,较为准确地提取任意方向的边缘。 相似文献
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Devi Devapal S. S. Kumar Christy Jojy 《Journal of the Indian Society of Remote Sensing》2017,45(3):443-450
Synthetic aperture radar (SAR) is a day and night, all weather satellite imaging technology. Inherent property of SAR image is speckle noise which produces granular patterns in the image. Speckle noise occurs due to the interference of backscattered echo from earth’s rough surface. There are various speckle reduction techniques in spatial domain and transform domain. Non local means filtering (NLMF) is the technique used for denoising which uses Gaussian weights. In NLMF algorithm, the filtering is performed by taking the weighted mean of all the pixels in a selected search area. The weight given to the pixel is based on the similarity measure calculated as the weighted Euclidean distance over the two windows. Non local means filtering smoothes out homogeneous areas but edges are not preserved. So a discontinuity adaptive weight is used in order to preserve heterogeneous areas like edges. This technique is called as discontinuity adaptive non local means filtering and is well-adapted and robust in the case of Additive White Gaussian Noise (AWGN) model. But speckle is a multiplicative random noise and hence Euclidean distance is not a good choice. This paper presents evaluation results of using different distance measures for improving the accuracy of the Non local means filtering technique. The results are verified using real and synthetic images and from the results it can be concluded that the usage of Manhattan distance improves the accuracy of NLMF technique. Non local approach is used as a preprocessing or post processing technique for many denoising algorithms. So improving NLMF technique would help improving many of the existing denoising techniques. 相似文献
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InSAR干涉图滤波方法研究 总被引：9，自引：0，他引：9
探讨多视滤波法、中值滤波法、基于梯度的自适应滤波、additive滤波法四种抑制干涉图噪声的滤波方法.多视滤波法平滑了影像数据,是以牺牲空间分辨率为代价的,通常这种滤波处理应用在从两个单视影像获得的复数影像处理中;作为一种传统的抑制噪声方法,中值滤波技术实质上是一种非线性信号处理技术,它假设噪声具有极端的数值,即在所定义的平滑模板内为最(较)大值或最(较)小值,因此它会使得干涉图丢失一些信息;基于梯度的自适应法是基于梯度的一种中值滤波,它使得边缘更加清晰,该方法可与中值滤波联合使用;Addtive滤波法强调根据局部噪声状况和使用方向平行窗口得到的滤波噪声边缘来自适应的滤除噪声,对于局部噪声状况由关联图来决定.这种方法尤其对高关联的干涉图最为可取. 相似文献
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本文在Freeman分解理论基础上,提出一种极化SAR数据相干斑滤波算法。该算法基于Freeman散射模型对原始极化SAR数据进行分解,以获得像素的散射类型和总功率值;在滤波窗口内选取与中心像素散射类型相同,总功率值接近的像素构成滤波同质区;并根据同质区的局部统计特性,应用线性最小均方滤波器进行滤波处理。试验表明,该算法在有效去除相干斑的同时,对极化和边缘等细节信息也有较好的保持效果。 相似文献
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针对全极化合成孔径雷达Pol SAR(Polarimetric Synthetic Aperture Radar)影像相干斑噪声严重的问题,提出了一种结合相似块匹配和线性最小均方误差原理的去噪方法。该方法首先在原始影像上实现相似块组的匹配,进而利用线性最小均方误差滤波器对影像块组进行滤波得到初始去噪结果;然后,同时利用原始影像和初始去噪影像的信息进行相似块组的重新匹配,并再次利用线性最小均方误差原理对重匹配影像块进行去噪,得到影像最终的去噪结果。利用模拟的Pol SAR影像和高分三号卫星Pol SAR影像进行了算法效果的验证。结果表明,去噪算法在显著抑制影像噪声水平的同时,也能较好地保持影像的边缘和极化特性等细节信息。 相似文献
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Sanjay Shitole Mayank Sharma Shaunak De Avik Bhattacharya Y. S. Rao B. Krishna Mohan 《Journal of the Indian Society of Remote Sensing》2017,45(3):451-462
In this paper, we propose an adaptive filtering technique for Synthetic Aperture Radar (SAR) images. A new windowing technique is introduced where the total window is divided into five equal sized overlapping sub-windows. The pixel to be filtered is a part of each of these sub-windows. A weighted mean of all sub-windows is computed for the pixel under consideration. The weights are accounted from a measure of heterogeneity calculated for each sub-windows. The filter is able to adapt automatically and adjust the speckle suppression strength based on local statistics. This allows the filter to preserve edges while strongly suppressing speckle over homogeneous areas. The proposed filter was compared with some well known SAR filtering techniques in terms of speckle suppression and edge preservation ability. Several experiments were performed on datasets acquired from both air-borne and space-borne SAR platforms. Some well known indices were used for quantitative comparison with other filters. Among the filters compared, the proposed filter shows good speckle suppression ability while still exhibiting reasonable edge preservation ability. 相似文献
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Spatial contextual feature plays an important role in high resolution remote sensing image. A new approach based on local variance analysis is introduced to spatial contextual feature extraction for change detection in this paper. In the proposed approach, the change magnitude between the paired central pixels of a local area (e.g., a 3 × 3 sliding window) in multitemporal images depends on surrounding pixels in the difference image, and this change magnitude is quantitatively measured based on the standard deviation of the difference image within the local area. This difference image contextual property may be useful particularly when high-resolution images are used. Finally, the change magnitude image is classified as a binary CD map by using SVM. This proposed approach is applied to SPOT-5 multitemporal datasets and two QuickBird multitemporal images from two case studies, which are quantitatively compared and validated. Experimental results show that the proposed approach is feasible. 相似文献