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1.
基于神经网络的图像混合滤波及融合算法研究   总被引:1,自引:1,他引:0  
当图像中同时存在高斯噪声和椒盐噪声时,单一的均值滤波或中值滤波很难达到最佳滤波效果。 分析了噪声特点和各种滤波方法的优势,提出了一种基于神经网络的图像混合滤波及融合算法:首先建立概率神经网络,检测椒盐噪声和高斯噪声点,并分别利用中值滤波和均值滤波去除噪声点,然后建立径向基函数神经网络,利用训练好的径向基函数神经网络融合 2 种不同滤波的图像,输出理想的融合图像。 Matlab 仿真实验结果表明,该算法有效去除混合噪声的同时,能很好地保护图像的边缘与细节,是一种有效的方法。  相似文献   

2.
针对在正电子发射断层成像中,经典的惩罚最小二乘算法和基于局部先验惩罚的改进算法不能有效地抑制噪声并保护图像边缘的问题,提出了一种新的各向异性扩散滤波非局部惩罚最小二乘重建算法(PLS-PDE).新算法首先对图像进行基于非局部二次先验的最小二乘估计,接下来对此估计值进行基于双向扩散系数的各向异性扩散滤波.所提出的算法综合了非局部先验与各向异性扩散滤波的优点.实验结果表明,新算法在抑制噪声和边缘保护方面取得了良好的折中,较大程度地改善了重建图像的质量.  相似文献   

3.
为了探究光学相干层析技术(optical coherence tomography,OCT)中图像散斑的降噪处理方法,以提高图像质量,于是采用猪胃和泡沫塑料管为对象,对比研究了中值滤波、维纳滤波、小波滤波和各向异性扩散法对OCT图像散斑的降噪效果,并且通过信噪比(SNR)、等效视数(ENL)和散斑指数(Speckle-index)三个指标评价去噪效果,以此来弥补视觉对比的不足.结果表明,各向异性扩散算法不仅对OCT图像的散斑噪声具有最好的降噪效果,而且也较有效地保持了图像边缘信息.  相似文献   

4.
基于阈值判断的自适应中值滤波算法   总被引:1,自引:0,他引:1  
针对标准的中值滤波算法在去除噪声与保留图像细节方面难以取舍的缺陷,在自适应中值滤波算法的基础上提出了一种改进的基于噪声点检测的自适应中值滤波算法.该算法在进行噪声点检测时采用了一种阈值判断法,充分利用了当前像素点与邻域像素点的灰度值之间的关系.结果表明,在噪声浓度较高时仍然可以区分噪声点与边缘点,滤波的同时有效地保护了图像的细节.  相似文献   

5.
去除脉冲噪声的自适应开关中值滤波   总被引:9,自引:0,他引:9  
为消除图像中的脉冲噪声,提出了自适应开关中值(ASM)滤波算法。该算法采用一种新的噪声检测方法将图像中的像素分为信号点和噪声点两类。对检测出的噪声点统计其个数并由此估算图像中的噪声密度,根据估计的噪声密度自适应确定滤波窗口尺寸,采用改进的中值滤波对检测出的噪声点进行处理;而信号点则保留其灰度值不予处理。对ASM滤波进行仿真实验,结果表明,它能在有效去除噪声的同时很好地保护图像细节,较传统中值滤波及其它改进中值滤波算法有更优的滤波性能。  相似文献   

6.
传统LOG边缘检测算法对合成孔径雷达图像进行边缘检测时,对噪声敏感,同时也易损坏部分低强度边缘。针对这一问题,提出了一种新型的 LOG边缘检测算法,首先采用双边滤波和自适应中值滤波来代替传统LOG算子中的高斯滤波,再计算平滑后图像的拉普拉斯,最后提取运算后的零交叉点作为图像的边缘。仿真实验表明,本文方法在脉冲噪声环境下具有显著的去噪效果,而且能较好地保护边缘,提高了检测精度,相对传统LOG算法具有更好地检测效果。  相似文献   

7.
一种椒盐噪声点的检测算法技术研究   总被引:1,自引:0,他引:1       下载免费PDF全文
王婷  吴亚锋  李仕云 《声学技术》2007,26(6):1245-1247
针对中值滤波算法虽然能够在很大程度上改善噪声带来的影响,但是使图像边缘变得模糊这一问题,提出了一种检测椒盐噪声的新算法。使用该算法对图像进行噪声检测后再对噪声点进行中值滤波能够有效地去除椒盐噪声。实验证明该算法具有明显的去噪能力,且当椒盐噪声比较严重时,也能够取得较好的滤波效果。  相似文献   

8.
图像去椒盐噪声滤波器的研究   总被引:1,自引:0,他引:1  
在图像平滑过程中,如何滤除噪声同时保护图像的细节是一个研究热点.本文提出并设计一种将十字窗和叉形窗有机结合的多窗口自适应中值滤波器(MWMF滤波器),可根据窗口内图像自身的形状,自适应地选择十字窗和叉形窗.在比较多窗口自适应中值滤波和形态滤波这两种滤波器的优缺点之后,还提出并设计了非线性组合滤波器.实验表明该滤波器滤除椒盐噪声的效果优于单独使用中值滤波或形态学滤噪,在椒盐噪声概率超过0.2时优势尤为明显.  相似文献   

9.
一种基于椒盐噪声图像的加权滤波算法研究   总被引:1,自引:0,他引:1  
针对中值滤波和其改进算法虽然能够在很大程度上改善噪声带来的影响,但是使图像边缘变得模糊这一问题,提出一种滤除椒盐噪声的加权滤波新算法。该算法定义中值相似度和空间临近度函数,并采用双阈值,根据阈值的范围,采用不同的方法获取权值。使用该算法对图像进行加权滤波不仅能够有效地去除椒盐噪声,而且尽可能的保存完整的图像边缘信息。  相似文献   

10.
为了滤除多种噪声,保持图象边缘,本文在稳健统计理论基础上,提出一种新的稳健非线性滤波器——自适应M滤波器。重点研究M滤波器的滤波特性,边缘保持特性和滤波参数的自适应性。在一维和二维含有尖锐边缘的噪声信号滤波中,评价了自适应M滤波器的性能。理论分析和实验结果表明,自适应M滤波器在噪声滤波和边缘细节保持方面均优于中值滤波器、滑动均值滤波器和α-裁剪均值滤波器。还研究了最大/最小估计滤波器(M)、广义排序统计滤波器(L)和秩排序统计滤波器(R)三类著名非线性滤波器的内在关系,得到一些有意义的结果。  相似文献   

11.
Yu Q  Liu X  Sun X 《Applied optics》1998,37(20):4504-4509
Generalized spin filters, including several directional filters such as the directional median filter and the directional binary filter, are proposed for removal of the noise of fringe patterns and the extraction of fringe skeletons with the help of fringe-orientation maps (FOM's). The generalized spin filters can filter off noise on fringe patterns and binary fringe patterns efficiently, without distortion of fringe features. A quadrantal angle filter is developed to filter off the FOM. With these new filters, the derivative-sign binary image (DSBI) method for extraction of fringe skeletons is improved considerably. The improved DSBI method can extract high-density skeletons as well as common density skeletons.  相似文献   

12.
Noise corrupts ultrasound images and degrades spatial and contrast resolutions. Hence, it is challenging to characterize the lesions precisely using ultrasound images. The present study aims to evaluate 67 denoising filters and select the best one for ultrasound image denoising. Seven test images were synthesized to evaluate the performance of filters at three different noise levels. Eleven full-reference quantitative image quality metrics (IQMs) were employed to evaluate the performance of the filters. A new filter evaluation method, Rank Analysis, was introduced and utilized at each noise level. The ten best filters with the smallest mean rank in all noise levels were defined for further analysis on real ultrasound images. The Rank Analysis was also employed for real ultrasound images, and filters were evaluated based on 14 IQMs (11 full-reference and three no-reference). Finally, the best filter was defined using the repeated measures analysis statistical test. According to the Rank Analysis results, the Spatial correlation (SCorr) filter obtained the best results with the mean rank scores±SD of 1 ± 0, which was significantly better than the other nine filters (p < 0.001). The second-best results were achieved by three filters, Bitonic, most homogeneous neighborhood, and Lee diffusion (p < 0.05). We concluded that SCorr is the best filter for ultrasound image denoising. It can be used in the pre-processing step before segmentation and diagnostic procedures. In addition, a new filter evaluation method, Rank Analysis, was introduced in this study, which is easy to use, fast, and provides reliable results. So, it can be used to evaluate newly developed filters in the future studies.  相似文献   

13.
Positron emission tomography (PET) is becoming increasingly important in the fields of medicine and biology. Penalized iterative algorithms based on maximum a posteriori (MAP) estimation for image reconstruction in emission tomography place conditions on which types of images are accepted as solutions. The recently introduced median root prior (MRP) favors locally monotonic images. MRP can preserve sharp edges, but a steplike streaking effect and much noise are still observed in the reconstructed image, both of which are undesirable. An MRP tomography reconstruction combined with nonlinear anisotropic diffusion interfiltering is proposed for removing noise and preserving edges. Analysis shows that the proposed algorithm is capable of producing better reconstructed images compared with those reconstructed by conventional maximum-likelihood expectation maximization (MLEM), MAP, and MRP-based algorithms in PET image reconstruction.  相似文献   

14.
一种新的自适应非线性卡尔曼滤波算法   总被引:3,自引:1,他引:2  
为避免由于系统噪声统计特性不准确所导致的滤波性能下降问题,改进了一种基于新息的系统噪声方差调整方法,并将其与扩展卡尔曼滤波、Unscented 卡尔曼滤波和差分滤波相结合,形成自适应非线性卡尔曼滤波.将此方法应用到非线性测量光电跟踪系统中,并与采用基本非线性卡尔曼滤波进行性能对比.仿真实验结果证明该方法可以实时调整系统噪声方差,有效地避免由于系统噪声统计特性不准确所带来的滤波性能下降的问题,而且其性能明显优于基本非线性卡尔曼滤波.  相似文献   

15.
Modern X-ray imaging systems evolve toward digitization for reduced cost, faster time-to-diagnosis, and improved diagnostic confidence. For the digital X-ray systems, charge coupled device (CCD) technology is commonly used to detect and digitize optical X-ray image. This paper presents a novel soft-test/repair approach to overcome the defective pixel problem in CCD-based digital X-ray systems through theoretical modeling and analysis of the test/repair process. There are two possible solutions to cope with the defective pixel problem in CCDs: one is the hard-repair approach and another is the proposed soft-test/repair approach. Hard-repair approach employs a high-yield, expensive reparable CCD to minimize the impact of hard defects on the CCD, which occur in the form of noise propagated through A/D converter to the frame memory. Therefore, less work is needed to filter and correct the image at the end-user level while it maybe exceedingly expensive to practice. On the other hand, the proposed soft-test/repair approach is to detect and tolerate defective pixels at the digitized image level; thereby, it is inexpensive to practice and on-line repair can be done for noninterrupted service. It tests the images to detect the detective pixels and filter noise at the frame memory level and caches them in a flash memory in the controller for future repair. The controller cache keeps accumulating all the noise coordinates and preprocesses the incoming image data from the A/D converter by repairing them. The proposed soft-test/repair approach is particularly devised to facilitate hardware level implementation ultimately for real-time telediagnosis. Parametric simulation results demonstrate the speed and virtual yield enhancement by using the proposed approach; thereby highly reliable, yet inexpensive, soft-test/repair of CCD-based digital X-ray systems can be ultimately realized.  相似文献   

16.
17.
A new group of switching vector filters based on the non-causal linear prediction for the detection of impulse noise from colour images is presented. The proposed filters utilise the non-causal linear prediction coefficients obtained from the block-by-block autocorrelation function to find prediction vector pixel value at the centre of the filter window. Thirteen prediction coefficients are selected from the autocorrelation matrix obtained from a block of an image, and these coefficients are used to predict all pixels in that block. The difference between the predicted pixel and the original decides whether the pixel is corrupted with impulse noise. Extensive simulation experiments indicate that the new vector filters outperform the other vector filters currently used to eliminate impulse noise from colour images.  相似文献   

18.
自然环境下路面裂缝的识别   总被引:2,自引:0,他引:2  
论文提出了一种基于分数阶微分和图像形态学的路面裂缝检测算法。分数阶微分能有效增强信号中、高频部分,非线性保留信号的低频部分,通过构建分数阶微分掩模算子,增强裂缝信息特别是平滑区域中弱信号信息。利用图像形态学算子提取裂缝,通过组合中值滤波去除孤立噪声点。实验结果表明,该算法比传统算法能更有效地检测出细小裂缝信息,是一种具有较强鲁棒性且高效实用算法。  相似文献   

19.
Bronnikov AV  Duifhuis G 《Applied optics》1998,37(20):4437-4448
We consider an application of the wavelet transform to image processing in x-ray imaging and three-dimensional (3-D) tomography aimed at industrial inspection. Our experimental setup works in two operational modes-digital radiography and 3-D cone-beam tomographic data acquisition. Although the x-ray images measured have a large dynamic range and good spatial resolution, their noise properties and contrast are often not optimal. To enhance the images, we suggest applying digital image processing by using wavelet-based algorithms and consider the wavelet-based multiscale edge representation in the framework of the Mallat and Zhong approach [IEEE Trans. Pattern Anal. Mach. Intell. 14, 710 (1992)]. A contrast-enhancement method by use of equalization of the multiscale edges is suggested. Several denoising algorithms based on modifying the modulus and the phase of the multiscale gradients and several contrast-enhancement techniques applying linear and nonlinear multiscale edge stretching are described and compared by use of experimental data. We propose the use of a filter bank of wavelet-based reconstruction filters for the filtered-backprojection reconstruction algorithm. Experimental results show a considerable increase in the performance of the whole x-ray imaging system for both radiographic and tomographic modes in the case of the application of the wavelet-based image-processing algorithms.  相似文献   

20.
针对检测超声图像的边缘问题,介绍了一种基于Gabor奇部滤波器进行边缘检测的综合方法。为了去除图像噪声,首先进行基于小波变换和中值滤波的降噪处理,然后利用高斯函数平滑图像。在边缘检测过程中,使用Gabor奇部滤波器检测边缘。最后,使用非最大值抑制得到最终结果。结果表明该方法是对超声图像进行边缘检测的一种有用方法。当然,该方法也具有普遍性,可以应用到其他图像。  相似文献   

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