基于运动显著性的移动镜头下的运动目标检测

针对移动镜头下的运动目标检测中的背景建模复杂、计算量大等问题,提出一种基于运动显著性的移动镜头下的运动目标检测方法,在避免复杂的背景建模的同时实现准确的运动目标检测。该方法通过模拟人类视觉系统的注意机制,分析相机平动时场景中背景和前景的运动特点,计算视频场景的显著性,实现动态场景中运动目标检测。首先,采用光流法提取目标的运动特征,用二维高斯卷积方法抑制背景的运动纹理;然后采用直方图统计衡量运动特征的全局显著性,根据得到的运动显著图提取前景与背景的颜色信息;最后,结合贝叶斯方法对运动显著图进行处理,得到显著运动目标。通用数据库视频上的实验结果表明,所提方法能够在抑制背景运动噪声的同时,突出并准确地检测出场景中的运动目标。     

Motion detection with pyramid structure of background model for intelligent surveillance systems

This paper proposes a pyramidal background matching structure for motion detection. The proposed method utilizes spectral, spatial, and temporal features to generate a pyramidal structure of the background model. After performing the background subtraction based on the proposed background model, the moving targets can be accurately detected at each frame of the video sequence. In order to produce high accuracy for the motion detection, the proposed method also further includes a noise filter based on Bezier curve to smooth noise pixels, after which the binary motion mask can be computed by the proposed threshold function. Experimental results demonstrate that the proposed method substantially outperforms existing methods by perceptional evaluation.     

A robust framework for joint background/foreground segmentation of complex video scenes filmed with freely moving camera

This paper explores a robust region-based general framework for discriminating between background and foreground objects within a complex video sequence. The proposed framework works under difficult conditions such as dynamic background and nominally moving camera. The originality of this work lies essentially in our use of the semantic information provided by the regions while simultaneously identifying novel objects (foreground) and non-novel ones (background). The information of background regions is exploited to make moving objects detection more efficient, and vice-versa. In fact, an initial panoramic background is modeled using region-based mosaicing in order to be sufficiently robust to noise from lighting effects and shadowing by foreground objects. After the elimination of the camera movement using motion compensation, the resulting panoramic image should essentially contain the background and the ghost-like traces of the moving objects. Then, while comparing the panoramic image of the background with the individual frames, a simple median-based background subtraction permits a rough identification of foreground objects. Joint background-foreground validation, based on region segmentation, is then used for a further examination of individual foreground pixels intended to eliminate false positives and to localize shadow effects. Thus, we first obtain a foreground mask from a slow-adapting algorithm, and then validate foreground pixels (moving visual objects + shadows) by a simple moving object model built by using both background and foreground regions. The tests realized on various well-known challenging real videos (across a variety of domains) show clearly the robustness of the suggested solution. This solution, which is relatively computationally inexpensive, can be used under difficult conditions such as dynamic background, nominally moving camera and shadows. In addition to the visual evaluation, spatial-based evaluation statistics, given hand-labeled ground truth, has been used as a performance measure of moving visual objects detection.     

基于贝叶斯决策的运动目标检测方法

传统混合高斯背景建模存在难以解决背景复杂以及阴影等因素影响视频运动目标检测效果的问题,为此提出了一种基于贝叶斯决策的运动目标检测方法。该方法利用帧间差分进行像素变化检测,将像素粗分为变化像素和非变化像素;对于变化像素中的运动点和静止点,通过统计确立有效的数据结构,其中显著颜色分布统计量用来描述静止点,而显著颜色同现统计量描述运动点;从数据结构中提取颜色特征矢量,将特征矢量中的静止点和运动点按照贝叶斯决策规则进一步分类为背景点、前景点和颜色相似点。对颜色相似点进行局部加权处理以达到正确检测的目的;通过融合静止点集、运动点集和加权后的颜色相似点集结果提取出前景运动目标。仿真实验表明,该方法能够在不同复杂背景下较准确地检测出视频中的运动目标,相比传统算法具有较强的鲁棒性。     

运动显著性概率图提取及目标检测

目的 动态场景图像中所存在的静态目标、背景纹理等静态噪声,以及背景运动、相机抖动等动态噪声,极易导致运动目标检测误检或漏检。针对这一问题,本文提出了一种基于运动显著性概率图的目标检测方法。方法 该方法首先在时间尺度上构建包含短期运动信息和长期运动信息的构建时间序列组;然后利用TFT（temporal Fourier transform）方法计算显著性值。基于此,得到条件运动显著性概率图。接着在全概率公式指导下得到运动显著性概率图,确定前景候选像素,突出运动目标的显著性,而对背景的显著性进行抑制;最后以此为基础,对像素的空间信息进行建模,进而检测运动目标。结果 对提出的方法在3种典型的动态场景中与9种运动目标检测方法进行了性能评价。3种典型的动态场景包括静态噪声场景、动态噪声场景及动静态噪声场景。实验结果表明,在静态噪声场景中,F_score提高到92.91%,准确率提高到96.47%,假正率低至0.02%。在动态噪声场景中,F_score提高至95.52%,准确率提高到95.15%,假正率低至0.002%。而在这两种场景中,召回率指标没有取得最好的性能的原因是,本文所提方法在较好的包络目标区域的同时,在部分情况下易将部分目标区域误判为背景区域的,尤其当目标区域较小时,这种误判的比率更为明显。但是,误判的比率一直维持在较低的水平,且召回率的指标也保持在较高的值,完全能够满足于实际应用的需要,不能抵消整体性能的显著提高。另外,在动静态噪声场景中,4种指标均取得了最优的性能。因此,本文方法能有效地消除静态目标干扰,抑制背景运动和相机抖动等动态噪声,准确地检测出视频序列中的运动目标。结论 本文方法可以更好地抑制静态背景噪声和由背景变化（水波荡漾、相机抖动等）引起的动态噪声,在复杂的噪声背景下准确地检测出运动目标,提高了运动目标检测的鲁棒性和普适性。     

统计建模与对象更新机制相结合的背景减法

基于混合高斯模型（Gaussian Mixture Models,GMM）或码书模型（Codebook,CB）的传统背景建模算法和改进后的G-KDE算法被广泛地运用于运动目标检测中,但是在光照突变、非静止背景和运动目标短暂停留再运动的场景中不能正确地检测出运动目标。针对以上问题,提出了一种从静止摄像机的视频序列中检测运动目标的背景减算法。通过统计像素的经历作为时间序列,利用核密度估计判断背景像素是否受到运动目标干扰,使用K-均值聚类算法的两个连续阶段来确定可靠的背景区域,通过像素更新适应渐进的光照变化,提出一种基于对象的背景更新机制适应突然的光照变化以及非静止背景、鬼影等干扰。对实际摄取的视频进行了仿真实验,结果表明该算法比其他三种方法检测运动目标鲁棒性更好,准确性更高。     

Robust foreground detection in video using pixel layers

A framework for robust foreground detection that works under difficult conditions such as dynamic background and moderately moving camera is presented in this paper. The proposed method includes two main components: coarse scene representation as the union of pixel layers, and foreground detection in video by propagating these layers using a maximum-likelihood assignment. We first cluster into "layers" those pixels that share similar statistics. The entire scene is then modeled as the union of such non-parametric layer-models. An in-coming pixel is detected as foreground if it does not adhere to these adaptive models of the background. A principled way of computing thresholds is used to achieve robust detection performance with a pre-specified number of false alarms. Correlation between pixels in the spatial vicinity is exploited to deal with camera motion without precise registration or optical flow. The proposed technique adapts to changes in the scene, and allows to automatically convert persistent foreground objects to background and re-convert them to foreground when they become interesting. This simple framework addresses the important problem of robust foreground and unusual region detection, at about 10 frames per second on a standard laptop computer. The presentation of the proposed approach is complemented by results on challenging real data and comparisons with other standard techniques.     

基于背景减除法的视频序列运动目标检测

视频序列中运动目标的检测是目标识别、标记和追踪的重要组成部分,背景减除法是运动目标检测中被广泛应用的算法。针对光线变化、噪声和局部运动等影响运动目标检测效果的问题,提出一种基于背景减除法的视频序列运动目标检测算法。该算法结合背景减除法和帧间差分法,对当前帧像素点的运动状态进行判断,分别对静止和运动的像素点进行替换和更新,采用最大类间方差（Otsu）法对差分图像进行目标提取,并使用数学形态学运算去除目标中的噪声和冗余信息。实验结果表明,所提算法对于视频序列中运动目标的检测具有较好的视觉效果和较高的准确度,能够克服局部运动以及噪声等缺陷。     

一种适用于动态场景的运动目标提取新算法

在动态场景中提取运动目标是开展视频分析的关键问题,也是当前计算机视觉与图像处理技术领域中的热门课题。本文提出了一种适用于动态场景的运动目标提取新算法,算法先根据摄像机全局运动模型计算全局运动参数,再利用三帧差分法得到分割的前景。将分割为背景的像素点映射到邻近帧,求得各帧的像素点为背景时其高斯模型的均值及方差。最后利用粒子滤波预测出下一帧前景区域,计算各像素点为前景的概率,获得运动目标的视频分割结果。实验表明,本文算法有效地克服了由于全局运动模型参数估算偏差而导致的累积误差,能以更高精度实现跳水运动视频中的目标分割。     

一种动态场景下基于时空信息的视频对象提取算法

在实际应用中,许多视频序列具有运动背景,使得从其中提取视频对象变得复杂,为此提出了一种基于运动估计和图形金字塔的动态场景下的视频对象提取算法。该算法首先引入了相位相关法求取运动向量,因避免了视频序列中光照变化的影响,故可提高效率和稳健性;接着再根据参数模型进行全局运动估计来得到最终运动模板;然后利用图形金字塔算法对当前模板内图像区域进行空间分割,最终提取出语义视频对象。与现有算法相比,对于从具有动态场景的视频流中提取运动对象的情况,由于使用该算法能有效地避开精准背景补偿,因而不仅节省了计算量,而且提取出来的语义对象精度较高。实验表明,无论是对动态场景中刚性还是非刚性运动物体的分割,该算法都具有较好的效果。     

嵌入式系统中视频运动对象分割

提出了一种基于嵌入式系统的视频运动对象分割算法。首先利用差图像法抽取出运动的像素点,然后通过统计像素点的状态变化频率来区分运动物体和动态背景,并配合一权值状态矩阵将全局光照突变和动态背景像素自适应融合到背景中,从而分割出运动对象并进行跟踪。实验结果表明,该算法在嵌入式系统中实时跟踪运动目标取得了很好的效果。     

基于像素层背景模型的复杂场景运动目标检测

为了从复杂变化背景中鲁棒地检测、提取运动目标,提出一种基于像素层背景模型的运动目标检测算法。该算法采用快速均值漂移方法将背景帧上具有相同统计特性的像素划分为一个像素层,背景模型从而被表示为一组像素层,通过与邻域像素对应的层匹配来检测运动前景像素。实验结果表明,该方法可以实时、准确地检测运动目标,特别是在摄像机颤动等原因造成的背景时域不规则变化情况下,比经典的基于混合高斯背景模型的方法具有更好的检测效果。     

基于帧间差分法的动体特征速度聚类分析

针对智能视频监控中快速、准确的检测和识别运动物体的问题,提出了一种依据运动物体特征速度来检测识别动体以及解读其语义含义的算法。该方法以相对帧间差分法为基础,通过对预处理后的二值斑块图像的标记,计算斑块的像素长度作为其特征速度,并依据斑块特征速度的众数进行聚类分析,从斑块特征速度得到运动物体的特征速度语义解读和运动物体的检测识别。实验结果表明,斑块的特征速度不仅可以实现对运动物体的检测,而且通过聚类分析可以准确的得出动体特征的语义解读。用特征速度和众数聚类分析方法实现对运动物体的检测识别和语义解读相对于其他统计算法简单有效,便于智能摄像机的嵌入式开发。     

交互式分割视频运动对象的研究与实现

在 MPEG- 4视频编码标准中 ,为了实现基于视频内容的交互功能 ,视频序列的每一帧由视频对象面来表示 ,而生成视频对象面 ,需要对视频序列中运动对象进行有效分割 ,并跟踪运动对象随时间的变化 .在视频分割方法中 ,交互式分割视频对象能满足分割的效率与质量指标要求 ,因此提出了一种交互分割与自动跟踪相结合的方式来分割视频语义对象 ,即在初始分割时 ,依据用户的交互与形态学的分水线分割算法相结合提取视频对象轮廓 ,并用改进的轮廓跟踪方法有效提高视频对象轮廓的精度 ;对后续帧的跟踪 ,采用六参数仿射变换跟踪运动对象轮廓的变化 ,用平移估算的运动矢量作为初始值 ,计算六参数仿射变换的参数 .实验结果表明 ,该方法能有效地分割并跟踪视频运动对象     

Extracting mobile objects by sequential background detection on a video

This paper describes a technique for extracting moving objects from a video image sequence taken by a slowly moving camera as well as a fixed camera. The background subtraction method is effective for extracting moving objects from a video. But the latest background image should be employed for the subtraction in the mobile camera case and in order not to be influenced by the light intensity change. A temporal median technique is proposed in this paper which detects the background at every moment. The camera motion is estimated using a local correlation map and the temporal median filter is applied to the common image area among a set of successive image frames to extract the background. The technique was applied to the video images obtained at a junction from a hand-held camera and those taken at a pedestrians crossing by a camera fixed in a car and successfully detected pedestrians. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Detecting moving objects from a video taken by a moving camera using sequential inference of background images

This paper proposes a method of detecting moving objects using sequential inference of the background in a video taken with a moving camera. In the video taken using a moving camera, all positions of pixels change every frame. The positions of the background pixels in the image frame T are not the same as the positions of the background pixels in the image frame T + 1. 2D projective transform can be used to find changes in the pixel position every frame. Bilinear interpolation with four nearest pixels around the pixel in image frame T which corresponds to a pixel in the image frame T+1 can be used for creating a background model at T + 1. Having obtained the background model, a pixel in image frame T + 1 can be determined if it is a background pixel or a foreground pixel. The detection results of the proposed method are compared with the ground truth to determine the effectiveness of the proposed method.     

多信息动态融合的运动目标检测方法

针对基于视觉显著性的运动目标检测算法存在时空信息简单融合及忽略运动信息的问题,提出一种动态融合视觉显著性信息和运动信息的运动目标检测方法。该方法首先计算每个像素的局部显著度和全局显著度,并通过贝叶斯准则生成空间显著图;然后,利用结构随机森林算法预测运动边界,生成运动边界图;其次,根据空间显著图和运动边界图属性的变化,动态确定最佳融合权值;最后,根据动态融合权值计算并标记运动目标。该方法既发挥了显著性算法和运动边界算法的优势,又克服了各自的不足,与传统背景差分法和三帧差分法相比,检出率和误检率的最大优化幅度超过40%。实验结果表明,该方法能够准确、完整地检测出运动目标,提升了对场景的适应性。     

Bayesian modeling of dynamic scenes for object detection

Accurate detection of moving objects is an important precursor to stable tracking or recognition. In this paper, we present an object detection scheme that has three innovations over existing approaches. First, the model of the intensities of image pixels as independent random variables is challenged and it is asserted that useful correlation exists in intensities of spatially proximal pixels. This correlation is exploited to sustain high levels of detection accuracy in the presence of dynamic backgrounds. By using a nonparametric density estimation method over a joint domain-range representation of image pixels, multimodal spatial uncertainties and complex dependencies between the domain (location) and range (color) are directly modeled. We propose a model of the background as a single probability density. Second, temporal persistence is proposed as a detection criterion. Unlike previous approaches to object detection which detect objects by building adaptive models of the background, the foregrounds modeled to augment the detection of objects (without explicit tracking) since objects detected in the preceding frame contain substantial evidence for detection in the current frame. Finally, the background and foreground models are used competitively in a MAP-MRF decision framework, stressing spatial context as a condition of detecting interesting objects and the posterior function is maximized efficiently by finding the minimum cut of a capacitated graph. Experimental validation of the proposed method is performed and presented on a diverse set of dynamic scenes.     

拥挤场景下基于密集轨迹对准及其运动影响描述符的异常活动检测

针对现有异常活动检测算法对拥挤场景下的目标跟踪和描述能力不足的问题,文中提出基于密集轨迹对准及其运动影响描述符的算法,捕捉视频目标运动的关键信息.密集轨迹保证对视频运动目标的有效提议,沿着轨迹的方向提取与轨迹对准的运动影响描述符.最后提出完整框架,准确检测全局和局部的异常活动.在UCSD公共数据集上的实验证明文中方法性能较优.     

基于时空背景差的运动目标检测算法

假定图像序列的背景图像已经获得,提出一种基于时空背景差的运动目标检测算法.该算法融合背景差分、基于时间信息的帧间差分及基于空间信息的背景差分信息,得到真实运动物体的运动种子点,认为背景差分图像中包含运动种子点的连通区域为真实的前景目标,从而可以检测出正确而完整的前景目标.仿真实验表明,该算法可以避免背景模型对场景的表征不足及背景更新阶段造成的错误检测,即使在场景中存在微小运动的复杂环境下,仍能实现准确的运动分割.