New Fuzzy Color Median Filter

Median filters are widely used in color image processing. In this paper a new fuzzy median filter is introduced, suitable for the removal of impulse noise in color images. In order to apply a median operator, some kind of ordering of vectors is required. Thus, a vector ordering scheme in the HSV color space using fuzzy if-then rules is described and then the median value operator is defined. The weighted fuzzy median is also studied. This filter performs significantly better in impulse noise removal, compared to other reported median filters. Experimental and comparative results of the application of the proposed filter and other similar reported filters, exhibit the superiority of the proposed method when applied to degraded color images.     

等级阈值的彩色图像矢量中值滤波

为消除彩色图像中的脉冲噪声,提出一种新的基于等级阈值的矢量中值滤波器。该滤波器设计了一组随滤波窗口内当前像素排序位置而等级变化的阈值,并根据当前像素与经典矢量滤波器输出的距离差值来判断噪声像素的存在。仿真实验证明,该方法较其他非开关型和开关型矢量中值滤波器能更好保存原图像细节和消除脉冲噪声。     

Mean shift denoising of point-sampled surfaces

This paper presents an anisotropic denoising/smoothing algorithm for point-sampled surfaces. Motivated by the impressive results of mean shift filtering on image denoising, we extend the concept to 3D surface smoothing by taking the vertex normal and the curvature as the range component and the vertex position as the spatial component. Then the local mode of each vertex on point-based surfaces is computed by a 3D mean shift procedure dependent on local neighborhoods that are adaptively obtained by a kdtree data structure. Clustering pieces of point-based surfaces of similar local mode provides a meaningful model segmentation. Based on the adaptively clustered neighbors, we finally apply a trilateral point filtering scheme that adjusts the position of sample points along their normal directions to successfully reduce noise from point-sampled surfaces while preserving geometric features.     

基于滤波器叠加的彩色图像矢量中值滤波方法

滤波是整个图像处理过程中的一个重要环节。矢量中值滤波方法在彩色图像滤波中使用广泛。为了达到更好的滤波效果,针对彩色图像中噪声的特点和传统滤波方法存在的不足,提出了一种改进的基于滤波器叠加的彩色图像矢量中值滤波算法。该算法借助矢量中值滤波方法的优点,使用双滤波器进行叠加,对彩色图像实现滤波。实验结果表明,该算法实现简单,运算量小。滤波过程中能在抑制噪声的同时很好地保留原图像信息。利用滤波器叠加,取得了较好的滤波效果。     

基于滤波器叠加的彩色图像矢量中值滤波方法

滤波是整个图像处理过程中的一个重要环节.矢量中值滤波方法在彩色图像滤波中使用广泛.为了达到更好的滤波效果,针对彩色图像中噪声的特点和传统滤波方法存在的不足, 提出了一种改进的基于滤波器叠加的彩色图像矢量中值滤波算法.该算法借助矢量中值滤波方法的优点,使用双滤波器进行叠加,对彩色图像实现滤波.实验结果表明,该算法实现简单,运算量小.滤波过程中能在抑制噪声的同时很好地保留原图像信息.利用滤波器叠加,取得了较好的滤波效果.     

基于支持向量机的改进中值滤波算法

对椒盐噪声的特点以及标准中值滤波算法存在的不足,提出一种基于支持向量机的改进中值滤波算法. 该算法首先对噪声图像进行中值滤波,并对滤波后图像去模糊化,然后用支持向量机分类确定去模糊化后图像中灰度值为最大值或最小值的像素点是否为噪声点,最后通过支持向量机回归预测将噪声点恢复为原始信号. 仿真实验及仿真结果分析表明该算法可以有效地去除椒盐噪声,且有较高的峰值信噪比.     

一种新的基于噪声点检测的脉冲噪声去噪算法

中值滤波是广泛应用于去除脉冲噪声的一种非线性去噪方法,但是单一地使用中值滤波方法去除脉冲噪声会造成图像细节信息的丢失,从而使图像变得模糊。基于噪声点检测的脉冲噪声滤波方法可以在滤除噪声的同时有效地保持图像的细节信息。该文在此基础上提出了一种新的基于噪声点检测的脉冲噪声滤波算法,该算法在检测噪声点时用被检测点的中值滤波结果作为判定该点是否为噪声点的依据。而在滤除被检测到的噪声点时,采用的是迭代的中值滤波算法。从实验结果中可以看到,与其它中值滤波算法相比,该文的算法在去除脉冲噪声时能取得较好的效果。     

保特征的联合滤波网格去噪算法

目的 在去噪的过程中保持网格模型的特征结构是网格去噪领域研究的热点问题。为了能够在去噪中保持模型特征,本文提出一种基于变分形状近似（VSA）分割算法的保特征网格去噪算法。方法 引入变分形状近似分割算法分析并提取噪声网格模型的几何特征,分3步进行去噪。第1步使用变分形状近似算法对网格进行分割,对模型进行分块降噪预处理。第2步通过分析变分形状近似算法提取分割边界中的特征信息,将网格划分为特征区域与非特征区域。对两个区域用不同的滤波器联合滤波面法向量。第3步根据滤波后的面法向量,使用非迭代的网格顶点更新方法更新顶点位置。结果 相较于现有全局去噪方法,本文方法可以很好地保持网格模型的特征,引入的降噪预处理对于非均匀网格的拓扑结构保持有着很好的效果。通过对含有不同程度高斯噪声的网格模型进行实验表明,本文算法无论在直观上还是定量分析的结果都相较于对比的方法有着更好的去噪效果,实验中与对比算法相比去噪效果提升15%。结论 与现有的网格去噪算法对比,实验结果表明本文算法在中等高斯噪声下更加鲁棒,对常见模型有着比较好的去噪效果,能更好地处理不均匀采样的网格模型,恢复模型原有的特征信息和拓扑结构。     

一种改进的脉冲噪声滤波方法

由于数字图像在生成与传输过程中容易受到脉冲噪声的污染,往往造成后续处理难以为继。为了改善图像质量,需要对图像进行去噪处理。针对传统中值滤波及其它非线性滤波方法在去除图像脉冲噪声时存在的不足,本文提出了一种改进的去噪方法:在滤波之前进行一次脉冲噪声检测,确定受到噪声污染的像素点,并进行记录标识;然后根据检测结果进行改进的中值滤波:只对判断为噪声点的像素进行处理,不仅考虑了标准中值,也分情况利用了中值的前一个值和中值的后一个值的信息。实验表明,改进方法不仅在滤除脉冲噪声方面相比其他非线性滤波有很大改进,而且它可以更好地保护图像的细节特性,对图像的后续处理有很好的价值。     

A cascaded approach for feature-preserving surface mesh denoising

Mesh denoising is crucial for improving noisy meshes acquired from scanning devices and digitization processes. This paper proposes a general, robust approach for mesh denoising by using a combination of bilateral filtering, feature recognition, anisotropic neighborhood searching, and surface fitting and projection techniques. Motivated by the bilateral filtering from image processing applications, we develop a new bilateral filter operating on the normal vector fields of the mesh. Then, we detect mesh features and classify mesh vertices into non-feature vertices and feature vertices. The corresponding anisotropic neighborhoods for each vertex are searched by constructing a weighted dual graph, over which biquadratic Bezier surface patches are fitted and projected. The projection points are averaged to update each vertex of the mesh. The steps above are repeated iteratively until convergence, i.e., the Hausdorff distance between two sequential denoised meshes is less than a pre-defined threshold. A number of examples presented in the paper demonstrate that our method generally yields visually and numerically better denoising results, compared with the state-of-the-art methods.     

A hybrid image restoration approach: fuzzy logic and directional weighted median based uniform impulse noise removal

In this paper, a hybrid image restoration technique based on fuzzy logic and directional weighted median is presented. The proposed technique consists of noise detection and fuzzy filtering processes to detect and remove uniform (random-valued) impulse noise while preserving the image details efficiently. In order to preserve image details such as edges and texture information, a two-stage robust noise detection is presented in this paper. Pixels detected as noisy by both the noise detection stages are considered for noise removal by the fuzzy filtering process, which utilizes the direction based weighted median to construct fuzzy membership function, which is the main contributing factor in noise removal and detail preservation. Extensive experimentation shows that the proposed technique performs significantly better than state-of-the-art filters based on peak signal-to-noise ratio, structural similarity index measure and subjective evaluation criteria.     

一种基于选点的可变滤波窗口中值滤波算法

中值滤波是一种应用广泛的滤波方法。该文提出了一种改进的中值滤波算法。该算法对中值滤波进行了两方面的改进,一方面基于选点的方法,不对所有的点进行滤波;另一方面在对中值滤波的窗口进行可变处理。与中值滤波相比,它具有更好的平滑噪声和边缘保持功能,而且能有效地滤除图像中的随机噪声。     

Histogram-based fuzzy filter for image restoration

In this paper, we present a novel approach to the restoration of noise-corrupted image, which is particularly effective at removing highly impulsive noise while preserving image details. This is accomplished through a fuzzy smoothing filter constructed from a set of fuzzy membership functions for which the initial parameters are derived in accordance with input histogram. A principle of conservation in histogram potential is incorporated with input statistics to adjust the initial parameters so as to minimize the discrepancy between a reference intensity and the output of defuzzification process. Similar to median filters (MF), the proposed filter has the benefits that it is simple and it assumes no a priori knowledge of specific input image, yet it shows superior performance over conventional filters (including MF) for the full range of impulsive noise probability. Unlike in many neuro-fuzzy or fuzzy-neuro filters where random strategy is employed to choose initial membership functions for subsequent lengthy training, the proposed filter can achieve satisfactory performance without any training.     

彩色图像迭代滤波算法

对于被脉冲噪声污染的彩色图像,基于噪声检测,提出了一系列迭代滤波算法。运用脉冲噪声检测器,估计出图像中的噪声像素,应用一系列后续滤波算法,只对检测出来的噪声像素进行滤波,而对非噪声像素（即信号像素）保持其值不变。传统的矢量滤波算法（矢量中值滤波、基本矢量方向滤波和方向距离滤波）加以改进后可作为后续的滤波算法。实验结果表明,这些新的滤波算法与传统滤波算法相比,在有效消除噪声的同时,更能够保留图像中的边缘和细节特征。     

基于四元数旋转的开关型矢量中值滤波器

矢量中值滤波器是一种经典和高效的矢量滤波器,主要用于消除彩色图像中的冲击噪声。然而VMF没有区分细线条和噪声的能力,它往往把细线条当成噪声而过滤掉。本文利用四元数旋转理论,模仿Laplacian算子,提出一种用于检测彩色图像中的冲击噪声的算法,并结合传统的VMF构造出一个新颖的开关型矢量中值滤波器。实验结果表明,新的滤波器不仅能有效地保护细线条和边界等细节信息,而且其滤波性能也明显胜过传统的VMF和一些经典的及最近开发的矢量滤波器。     

中子集型自适应中值滤波器

消除脉冲噪声通常采用中值滤波算法。尽管有许多中值滤波方法做了很大改进,但是,在噪声密度较高的情况下,图像滤波的结果仍然不能令人满意,因此,提出了一种新型中值算法。首先对滤波窗口中的像素进行分类,然后确定其中多元素子集的中子集,并且根据多元素子集的个数来决定是进行滤波还是扩大滤波窗口。最后,在仿真中,将该算法分别和几种中值滤波算法在数值和视觉上进行比较,实验结果显示,该算法能够有效地降低脉冲噪声并且保留了原始图像的更多细节。     

一种基于排序阈值的开关中值滤波方法

提出了一种基于排序阈值的开关中值滤波方法以克服图像滤波中去噪与细节保护的矛盾。该方法利用滤波窗口内像素点的排序信息，在极值中值滤波方法的基础上，将受脉冲噪声污染图像中的像素点进一步分为噪声点、边缘细节区和平坦区3种类型。通过对多种图像测试的统计结果，获得合适的分类器参数，然后利用类型判决，进行开关中值滤波，即对噪声点和平坦区进行中值滤波以得到良好的噪声滤除效果，而对边缘细节区不做处理以获得良好的细节保护效果。比较了标准中值滤波、极值中值滤波和本方法的结果。实验结果表明，本方法具有更好的效果。     

A new class of detail-preserving filters for image processing

A new class of median type filters for image processing is proposed. In the filters, linear FIR substructures are used in conjunction with the median operation. The root signals and noise attenuation properties of the FIR-median hybrid filters are analyzed and compared to representative edge preserving filtering operations. The concept of multilevel median operation is introduced to improve the detail preserving property of conventional median and the FIR-median hybrid filters. In the multilevel filters there exists a tradeoff between noise attenuation and detail preservation. The analysis and examples indicate that FIR-median hybrid filters preserve details better and are computationally much more efficient than the conventional median and the K-nearest neighbor averaging filters.     

基于CIELAB空间的开关型矢量中值滤波器

矢量中值滤波器VMF（Vector median filter）是一种经典和高效的矢量滤波器,主要用于消除彩色图像中的脉冲噪声.然而VMF没有区分细线条和噪声的能力,往往把细线条当成噪声而过滤掉.本文先将彩色图像从RGB空间变换到均匀颜色空间CIELAB中,然后模仿Laplacian算子,提出一个用于检测彩色图像中的脉冲噪声的算法,并结合传统的VMF构造出一个新颖的开关型矢量中值滤波器.实验表明,新的滤波器不仅能有效地保护细线条和边界等细节信息,而且其滤波性能也明显胜过传统的VMF和一些经典的、及最近开发的矢量滤波器.     

基于相关滤波器和最小二乘估计的目标跟踪方案

针对复杂背景下基于视觉图像的目标跟踪问题,提出一种结合相关滤波和最小二乘估计(LSE)的目标跟踪方案。首先,对已有视频帧进行初始化处理,并构建目标的几何失真图像模板,以此设计一个相关滤波器。然后,当采集到新视频帧时,根据之前的目标位置序列,利用LSE预测出该帧中的目标位置。接着,提取目标图像,并计算其与目标模板之间的相关性。最后,通过阈值来判断是否检测到真正的目标,并进行反馈用来更新目标模板。在GPU上实现该方案,并在几个视频序列上的实验结果表明,该方案能够准确跟踪目标,且对噪声和光照等环境因素具有很好的鲁棒性。