基于混合高斯模型的阴影去除算法

阴影去除是智能视频领域中运动目标识别的一项重要内容,其结果直接影响目标识别的准确性。针对当前基于纹理特征的阴影去除算法的不足,提出一种结合YCbCr颜色空间和混合高斯模型(GMM)的阴影去除算法。首先利用混合高斯模型提取出运动区域;然后通过分析运动区域的前景和背景在YCbCr颜色空间的差值统计特性,建立混合高斯阴影模型;最后根据高斯分布的概率分布规律,得到阴影分布特性,从而实现对阴影的去除。对于实验中的序列图像,所提算法有70%以上的阴影检测率。实验结果表明,所提方法能够在不同的场合快速有效地去除阴影,准确地提取运动目标。     

Implementation of Real-Time Vehicle Tracking in City-Scale Video Network

Tracking unexpected warning vehicles is required for quick response to security incident. To realize real-time vehicle tracking in a large-scale video surveillance network, a geospatial and temporal connection (GSTC) model is introduced to model the connection between videos. The transition time between videos is modeled by a Gaussian mixture model (GMM). With the developed plug-ins based on GSTC and GMM, the video streams of defined geospatial neighbors are automatically called in with the video stream that the object appears in during the tracking process. Experiments show that the ratio of success of real-time tracking is largely increased.     

Consistent color and detail transfer from multiple source images for video and images

In this paper, we propose a method to jointly transfer the color and detail of multiple source images to a target video or image. Our method is based on a probabilistic segmentation scheme using Gaussian mixture model (GMM) to divide each source image as well as the target video frames or image into soft regions and determine the relevant source regions for each target region. For detail transfer, we first decompose each image as well as the target video frames or image into base and detail components. Then histogram matching is performed for detail components to transfer the detail of matching regions from source images to the target. We propose a unified framework to perform both color and detail transforms in an integrated manner. We also propose a method to maintain consistency for video targets, by enforcing consistent region segmentations for consecutive video frames using GMM-based parameter propagation and adaptive scene change detection. Experimental results demonstrate that our method automatically produces consistent color and detail transferred videos and images from a set of source images.     

粒子滤波的视频目标跟踪算法研究

目标跟踪是计算机视觉和图像处理的一个重点课题,在视频监控、机器人视觉导航以及智能交通控制中具有广泛的应用前景.通过粒子滤波技术,研究了如何整合颜色特征、前景信息和积分图运算等技术实现视频目标跟踪的粒子滤波算法.在对目标进行分割中采用了混合高斯背景建模方法;同时结合积分直方图的计算方法对颜色特征进行分段统计及相互遮挡的判断,实现基于粒子滤波的目标跟踪算法的优化,解决跟踪中诸如遮挡、光照变化、背景干扰、尺寸变化等难以解决的问题.实验结果表明提出的方法达到了预期目标.     

基于贝叶斯通用背景模型的图像标注

在高斯图特征提取过程中,通用背景模型(Universal background model, UBM) 方法常用于根据总体分布估计每一幅图像中特征点分布的高斯混合模型(Gaussian mixture model, GMM)参数. 然而UBM估计的GMM权重参数中有很多接近零的数值,它们所对应的高斯分量对分布估计贡献小却又都参与了计算, 因此UBM的时间复杂度较高. 为解决这个问题,本文提出Bayes UBM方法. 通过引入受限的对称Dirichlet分布来描述GMM权重参数的先验分布,利用Bayes最大后验概率对GMM参数集进行估计. 实验表明Bayes UBM方法不仅有效地降低了时间复杂度,而且提高了Corel数据集上的图像标注精度.     

基于高斯混合模型的色彩转换

在将彩色图像转变为黑白图像的应用中,传统的彩色一灰度转换方法无法有效地传递色彩差异反映的视觉信息,其时间开销太大或者需要人工交互,因此目前并没有得到实际推广应用.为了解决这些问题,提出一种基于多元高斯混合模型(GMM)的彩色一灰度转换算法.该算法从人眼对彩色图像的感知机制出发,把对彩色图像中的视觉信息提取过程视为多维数据的分类问题,首先通过重采样抽取训练数据点集,然后引入GMM对彩色图像中的像素分布进行建模,通过一个改进的Gibbs采样彩色图像建模算法取得模型参数,并实现高斯混合元数目的自动确定;最终实现彩色一灰度转换操作.实验证明,该算法能够较快地完成彩色一灰度的自动转换.并有效地保留了彩色图像中由色彩传递的视觉信息.     

KPCA for semantic object extraction in images

In this paper, we kernelize conventional clustering algorithms from a novel point of view. Based on the fully mathematical proof, we first demonstrate that kernel KMeans (KKMeans) is equivalent to kernel principal component analysis (KPCA) prior to the conventional KMeans algorithm. By using KPCA as a preprocessing step, we also generalize Gaussian mixture model (GMM) to its kernel version, the kernel GMM (KGMM). Consequently, conventional clustering algorithms can be easily kernelized in the linear feature space instead of a nonlinear one. To evaluate the newly established KKMeans and KGMM algorithms, we utilized them to the problem of semantic object extraction (segmentation) of color images. Based on a series of experiments carried out on a set of color images, we indicate that both KKMeans and KGMM can offer more elaborate output than the conventional KMeans and GMM, respectively.     

Scribble-based object segmentation with modified gaussian mixture models

In this paper, we present an interactive segmentation method, designed to help the user to extract an object of interest from an image. The proposed approach adopts the scribble-based segmentation paradigm. The user interaction consists of specifying a set of lines, corresponding to both foreground and background scribbles. The segmentation process is based on color distributions, estimated with Gaussian mixture models (GMM). We show that such a technique presents some limitations when dealing with compressed images, even for relatively high quality compression factors: in this case, blocking artifacts may degrade the segmentation results. In order to overcome such a drawback, a modified GMM model, which re-shapes the Gaussian mixture based on the eigenvalues of the GMM components, is proposed. The experimental evaluation, carried out on a corpus of various images with different characteristics and textures, demonstrates the superiority of the modified GMM model which is able to appropriately take into account compression artifacts.     

基于隐条件随机场的自适应视频分割算法

视频目标分割是视频监视与视频目标跟踪、视频目标识别以及视频编辑的基础. 本文提出了一种基于隐条件随机场 (Hidden conditional random fields, HCRF) 的自适应视频分割算法, 利用 HCRF 模型对视频序列中的时空邻域关系建模. 使用在线学习的方式对相应的参数进行调整, 实现对时空邻域约束关系的权重调整, 提高视频目标分割细节上的效果. 大量的数据测试表明, 与高斯混合模型 (Gaussian mixture model, GMM) 和联合时空的马尔可夫随机场 (Markov random fields, MRF) 等算法相比, 该算法的分割错误率分别降低了23\%和19\%.     

基于OpenCV的视频运动目标检测及其应用研究

高斯混合模型已经成为对视频利用背景减除法进行运动目标检测的最多的一种背景建模模型,也成为一种标准模型。首先对高斯混合模型的理论框架进行了分析,然后采用OpenCV技术实现高斯混合模型来检测视频运动目标,实验结果表明高斯混合模型对摄像头静止的道路监控视频运动目标检测具有较好的效果。最后以该运动目标检测技术为基础设计了一种智能视频监控系统,该系统具有较好的实用性。     

基于高斯混合模型的结核菌图像检测

结核病是严重危害人类健康的一类疾病。通过计算机图像处理手段进行自动检测结核菌计数可以大幅提高医生诊断效率。高斯混合模型是单一高斯分布的延伸,是使用多个高斯分布加权来拟合给定的数据样本,通过确定拟合参数确定每个样本的分类概率。该文首先通过向量量化算法对图像预处理,降低所需处理数据量,然后从HSV、CIEL＊a＊b＊、YCbCr颜色空间提取特征分量并送入高斯混合模型进行训练。根据实验结果,高斯混合模型比其他无监督分类算法（如K-means算法）准确度更高,与有监督的分类算法（如朴素贝叶斯分类算法）相比可以简化训练样本的制作,具有一定优势。     

基于混合高斯模型与码本算法的前景目标检测

提出一种基于混合高斯模型(GMM)与码本算法的前景目标检测方法。利用GMM进行背景图像建模并初步提取前景对象,对背景图像进行码本学习,将码本建模得到的前景对象与GMM得到的前景对象相融合,根据前后2次帧间差分得到前景对象的比例关系,自适应地更新高斯参数和扩展码字,得到前景对象目标。实验结果表明,该方法实时性好,可消除视频序列中的阴影和鬼影,提取完整的前景对象。     

基于高斯混合模型的空间域背景

运动检测和背景分离技术是智能视频监控系统中的一项关键技术。由于目前广泛使用的高斯混合模型背景分离法是在像素域的时间尺度上对像素进行分类,因此常常造成误判,且无法解决阴影问题。为解决此问题,提出了一种空间域上的背景分离法。该方法首先将像素检测从像素域拓展至空间域的局部窗口内;然后在得到前景点集后,再将此空间域检测思想结合像素亮度特征运用到阴影消除中;最后,对经典模型的部分参数估计方法进行了修改。相关的实验结果证明,该方法可用于提高背景分离的检测精度和实现运动物体阴影消除。     

Robust object tracking under appearance change conditions

We propose a robust visual tracking framework based on particle filter to deal with the object appearance changes due to varying illumination, pose variantions, and occlusions. We mainly improve the observation model and re-sampling process in a particle filter. We use on-line updating appearance model, affine transformation, and M-estimation to construct an adaptive observation model. On-line updating appearance model can adapt to the changes of illumination partially. Affine transformation-based similarity measurement is introduced to tackle pose variantions, and M-estimation is used to handle the occluded object in computing observation likelihood. To take advantage of the most recent observation and produce a suboptimal Gaussian proposal distribution, we incorporate Kalman filter into a particle filter to enhance the performance of the resampling process. To estimate the posterior probability density properly with lower computational complexity, we only employ a single Kalman filter to propagate Gaussian distribution. Experimental results have demonstrated the effectiveness and robustness of the proposed algorithm by tracking visual objects in the recorded video sequences.     

基于多种类视觉特征的混合高斯背景模型

Stauffer等人提出的混合高斯背景减除建模技术及其改进算法在真实场景的运动目标检测系统中取得了较好的检测效果且被人们广泛应用。然而,此类方法通常采用单一的颜色视觉特征进行建模。当运动目标的表观颜色和背景场景的表观颜色相近时,检测准确度会大大降低。对于场景亮度条件的突变而引起的前景噪声,即使采用模型更新机制,也不能有效及时的去除。针对这些不足,提出一种基于颜色、边缘和纹理视觉特征的混合高斯建模技术。新的建模特征能够很好的描述背景区域的本质,对前景目标有着非常好的区分力,并且采用准确率和召回率对实验结果进行定量分析。实验分析表明,新算法有效地解决了传统算法存在的问题。同时也为后继的高层视觉分析任务打下了良好的基础。     

Contextual motion field-based distance for video analysis

In this work, we propose a general method for computing distance between video frames or sequences. Unlike conventional appearance-based methods, we first extract motion fields from original videos. To avoid the huge memory requirement demanded by the previous approaches, we utilize the “bag of motion vectors” model, and select Gaussian mixture model as compact representation. Thus, estimating distance between two frames is equivalent to calculating the distance between their corresponding Gaussian mixture models, which is solved via earth mover distance (EMD) in this paper. On the basis of the inter-frame distance, we further develop the distance measures for both full video sequences. Our main contribution is four-fold. Firstly, we operate on a tangent vector field of spatio-temporal 2D surface manifold generated by video motions, rather than the intensity gradient space. Here we argue that the former space is more fundamental. Secondly, the correlations between frames are explicitly exploited using a generative model named dynamic conditional random fields (DCRF). Under this framework, motion fields are estimated by Markov volumetric regression, which is more robust and may avoid the rank deficiency problem. Thirdly, our definition for video distance is in accord with human intuition and makes a better tradeoff between frame dissimilarity and chronological ordering. Lastly, our definition for frame distance allows for partial distance.     

基于改进的高斯混合模型的运动目标检测

运动目标检测是实现目标跟踪、视频监控的基础.针对基于高斯混合模型的运动目标检测算法的不足,提出了一种基于分块思想和高斯模型个数自适应的改进高斯混合算法.利用对视频图像分块的思想,在提高目标检测效率的同时,实现对视频的滤波处理;并利用高斯混合模型中高斯分布个数自适应操作来降低算法复杂度,提高运动目标检测的速度.实验结果表明:该算法比传统高斯混合模型运动目标检测算法具有更快的检测速度和更好的检测效果,并降低了检测噪声,能有效地检测运动目标,适用于运动目标的实时检测.     

基于深度编解码网络的运动目标检测算法

运动目标检测算法在视频监控等领域应用广泛,但是现实场景中由于噪音、光照变化等因素导致背景复杂多变,传统的运动目标检测算法往往效果不佳. 为了提升算法效果,提出了一种新的基于深度编解码网络的运动目标检测算法,将问题转化为像素级的语义分割问题. 事先使用大量数据离线训练出一个编解码网络,来学习背景与视频帧之间的差异性,实际应用中首先使用高斯混合模型进行背景建模,之后将所得背景与视频帧作为网络输入即可直接获取检测结果. 该方法利用了深度卷积网络在抗噪及特征学习等方面的优点,无需进行复杂的参数调优即可实现高性能的运动目标检测. 我们在CDnet2014数据集上进行了实验评估,实验结果显示我们所提出的算法较原GMM算法有很大提升,甚至在一些场景中的表现优于现有的一些顶尖算法. 另外得益于非常简单的背景建模方法以及网络结构,我们的算法在使用GPU的情况下能够近乎实时地进行运动目标检测,实用性很强.     

Unsupervised Video Object Segmentation Based on Mixture Models and Saliency Detection

Neural Processing Letters - In this paper, we propose an unsupervised video object segmentation approach which is mainly based on a saliency detection method and the Gaussian mixture model with...