Adaptive shadow estimator for removing shadow of moving object

We propose an adaptive shadow estimator to detect and eliminate the shadow of a moving object while adapting to variation of illumination and the environment in an automatic manner. The proposed method discriminates between the shadow and the moving object by cascading three estimators which use the properties of chromaticity, brightness, and local intensity ratio. In the spatial adjustment step, the method compensates for accumulated errors in the cascading process. Experimental results show that our scheme can operate in real-time, outperforms existing methods, and rapidly adapts to variations in the environment.     

An evaluation of moving shadow detection techniques

Computational Visual Media - Shadows of moving objects may cause serious problems in many computer vision applications, including object tracking and object recognition. In common object detection...     

基于移动区域的快速粗模型阴影检测

阴影检测是运动车辆目标识别与追踪中非常重要的环节.结合基于颜色和模型的两种检测方法,提出一种基于移动区域的快速粗模型阴影检测方法.该方法首先通过改进的背景差分方法快速获取图像中的移动区域,然后在此基础上根据基于模型的方法建立阴影的粗模型,即快速确定阴影区域的粗略区域.阴影检测时只对该区域内的图像采用基于HSV颜色空间的方法进行分析处理.实验结果表明该方法可以有效地提高阴影检测的效率.     

车辆视频检测及阴影去除

针对智能交通系统的车辆检测问题,提出了一种运动车辆检测及阴影去除的方法。采用基于背景差与帧间差的方法来检测运动视频中的车辆,对背景差和帧间差检测出的车辆进行或运算得到运动目标。再对检测出的运动目标进行形态学处理,并结合色彩及阴影统计信息建立阴影模型,去除阴影。实验结果表明,该方法能够快速、准确地在动态视频中分割出运动车辆和阴影。     

一种自适应的运动目标阴影检测算法

在分析视频图像HSV差分图和差分图直方图的基础上,根据差分直方图中目标与阴影的像素分布特点,提出了一种基于最大类间方差的自适应加权阴影检测算法。实验表明,该算法具有检测精度高、效果好、适应性强和易于工程实现的特点。     

Efficient shadow detection by using PSO segmentation and region-based boundary detection technique

The Journal of Supercomputing - The presence of shadows in satellite images is inevitable, and hence, shadow detection and removal has become very essential. In this paper, a shadow detection...     

Moving shadow detection and removal for traffic sequences

Segmentation of moving objects in a video sequence is a basic task for application of computer vision. However, shadows extracted along with the objects can result in large errors in object localization and recognition. In this paper, we propose a method of moving shadow detection based on edge information, which can effectively detect the cast shadow of a moving vehicle in a traffic scene. Having confirmed shadows existing in a figure, we execute the shadow removal algorithm proposed in this paper to segment the shadow from the foreground. The shadow eliminating algorithm removes the boundary of the cast shadow and preserves object edges firstly; secondly, it reconstructs coarse object shapes based on the edge information of objects; and finally, it extracts the cast shadow by subtracting the moving object from the change detection mask and performs further processing. The proposed method has been further tested on images taken under different shadow orientations, vehicle colors and vehicle sizes, and the results have revealed that shadows can be successfully eliminated and thus good video segmentation can be obtained.     

基于超像素和局部颜色恒常性的自适应阴影去除

为快速有效地去除监控视频中运动目标的投射阴影,提出了一种基于超像素和阴影区域的局部颜色恒常性的自适应阴影去除算法。首先采用改进的简单线性迭代聚类算法将视频图像中的运动前景分割为互不重叠的超像素;然后计算了RGB颜色空间中背景与运动前景的亮度比率,并分析了阴影区域的局部颜色恒常性;在此基础上,以超像素为基本处理单元,计算亮度比率的标准差,并利用阴影区域标准差的特征及其分布规律提出基于拐点的自适应阈值算法检测并去除阴影。实验结果表明,该算法可以适用于多种真实场景下的阴影检测,且阴影检测率与目标识别率均超过85%;基于超像素处理可以大幅度降低算法的计算复杂度,该算法每帧平均处理时间为20 ms。该算法可以同时满足阴影去除对准确度、实时性和鲁棒性的要求。     

基于半监督学习的行人检测方法研究

本文提出了基于半监督学习的行人检测方法,用以解决大量的无标记样本问题。在集成分类器的训练过程中,选择BP神经网络分类器、SVM分类器和KNN分类器作为3个子分类器,利用协同训练机制对各个子分类器进行协同训练。针对半监督学习中误标记样本问题,引入富信息策略和辅助学习策略消除训练过程引入的噪声,同时充分利用无标记样例,进而提高分类器的分类精度。通过对测试集和实时视频进行的行人检测实验,证明了本文方法的可行性和有效性。     

行人视频检测中阴影检测与去除方法设计

设计了基于模糊神经网络的目标本体与阴影的自动分类器,将光谱特征值作为神经网络输入,用遗传算法对网络权值和模糊规则实时更新,并结合图像的空间特性对去除结果进行修正.实验结果表明,应用该方法能有效去除阴影,并可提高行人视频检测的准确率.     

Physical models for moving shadow and object detection in video

Current moving object detection systems typically detect shadows cast by the moving object as part of the moving object. In this paper, the problem of separating moving cast shadows from the moving objects in an outdoor environment is addressed. Unlike previous work, we present an approach that does not rely on any geometrical assumptions such as camera location and ground surface/object geometry. The approach is based on a new spatio-temporal albedo test and dichromatic reflection model and accounts for both the sun and the sky illuminations. Results are presented for several video sequences representing a variety of ground materials when the shadows are cast on different surface types. These results show that our approach is robust to widely different background and foreground materials, and illuminations.     

Adaptive semi-supervised learning on labeled and unlabeled data with different distributions

Developing methods for designing good classifiers from labeled samples whose distribution is different from that of test samples is an important and challenging research issue in the fields of machine learning and its application. This paper focuses on designing semi-supervised classifiers with a high generalization ability by using unlabeled samples drawn by the same distribution as the test samples and presents a semi-supervised learning method based on a hybrid discriminative and generative model. Although JESS-CM is one of the most successful semi-supervised classifier design frameworks based on a hybrid approach, it has an overfitting problem in the task setting that we consider in this paper. We propose an objective function that utilizes both labeled and unlabeled samples for the discriminative training of hybrid classifiers and then expect the objective function to mitigate the overfitting problem. We show the effect of the objective function by theoretical analysis and empirical evaluation. Our experimental results for text classification using four typical benchmark test collections confirmed that with our task setting in most cases, the proposed method outperformed the JESS-CM framework. We also confirmed experimentally that the proposed method was useful for obtaining better performance when classifying data samples into either known or unknown classes, which were included in given labeled samples or not, respectively.     

交通场景中车辆的运动检测与阴影消除

提出一种算法框架实现对交通场景中运动车辆的分割。首先,提出一种基于颜色空间的浮动气球模型,用以解决监控场景的自适应背景建模问题,该方法解决了基于参数模型的背景建模方法无法检测驻留物体的问题,并可有效适应监控场景中的光照变化以实现自适应更新;其次,针对通过背景建模和背景差分得到的运动前景区域包含运动车辆阴影问题,提出一种新的阴影检测算法,该算法采用多特征融合的方法实现了对运动车辆的分割。实验结果分析表明,与其他方法相比,该算法框架在背景建模和阴影检测方法具有较好的效果。     

基于视频图像的运动目标阴影去除方法

针对运动目标检测中阴影的存在会导致目标形状扭曲、多个目标之间出现粘连等问题,提出一种基于视频图像的阴影去除方法。该方法在分析阴影产生机理的基础上,根据各像素点YUV空间上的像素模型,计算出带有阴影的目标相对于背景的失真系数,再根据设定的阈值区分出目标的实际轮廓和阴影区域,从而将目标阴影去除。实验结果表明,该方法能够快速检测和去除目标阴影,准确反映出目标的实际轮廓,并能够有效解决目标粘连问题。     

基于半监督学习和三支决策的入侵检测模型

针对现有的入侵检测模型在未知攻击上表现不佳,且标注数据极其有限的情况,提出一种基于半监督学习(SSL)和三支决策(3WD)的入侵检测模型——SSL-3WD.SSL-3WD模型通过3WD在信息不足情况下的优秀表现来满足SSL在数据信息的充分冗余性上的假设.首先利用3WD理论对网络行为数据进行分类,而后根据分类结果选择适当...     

Online web video topic detection and tracking with semi-supervised learning

With the pervasiveness of online social media and rapid growth of web data, a large amount of multi-media data is available online. However, how to organize them for facilitating users’ experience and government supervision remains a problem yet to be seriously investigated. Topic detection and tracking, which has been a hot research topic for decades, could cluster web videos into different topics according to their semantic content. However, how to online discover topic and track them from web videos and images has not been fully discussed. In this paper, we formulate topic detection and tracking as an online tracking, detection and learning problem. First, by learning from historical data including labeled data and plenty of unlabeled data using semi-supervised multi-class multi-feature method, we obtain a topic tracker which could also discover novel topics from the new stream data. Second, when new data arrives, an online updating method is developed to make topic tracker adaptable to the evolution of the stream data. We conduct experiments on public dataset to evaluate the performance of the proposed method and the results demonstrate its effectiveness for topic detection and tracking.     

基于半监督学习的跌倒检测系统设计

针对老人跌倒时的复杂运动情况,进行跌倒标注的较难实现,提出了基于Tri-training半监督算法的跌倒检测系统。本系统使用3D加速度传感器采集运动加速度数据,然后对数据进行特征提取与部分样本标注,使用Tri-training算法训练分类器,最后使用训练好的分类器进行跌倒识别。具体的数据采集传感器设计为可穿戴式设备,服务器端使用Java编写了一个服务器的程序实现对数据的分析与处理。实验结果表明：该方法使用了大量无标签数据的信息,有效提高了跌倒识别的准确率。实验结果表明：本系统能够满足老年人在日常生活中的需求,对于一些意外跌倒能够给予及时的检测与报警。     

基于背景重建的运动目标检测与阴影抑制

提出了一种静止摄像机条件下的运动目标检测和去除阴影的方法。该方法采用以图像亮度和能量大小为判断依据的分块背景重建方法来快速更新背景,并结合背景相减法,网格化连通域检测,形态学滤波等步骤来检测和提取运动目标,同时运用边缘检测获取阴影边缘信息,并结合形态学运算来去除阴影区域,恢复出完整物体目标。实验结果表明,该方法能够有效地检测出运动目标和抑制阴影。