基于运动估计的Kalman滤波视频对象跟踪

提出了一种利用Kalman滤波对运动目标的形心进行预测,从而实现视频对象跟踪的算法。首先进行视频对象分割,求出运动目标的形心。再利用视频序列中连续两帧的形心和运动矢量信息,用Kalman滤波对运动目标的形心在下一帧的位置进行预测,从而快速、有效地自动跟踪多个目标对象。实验结果表明,该算法对运动目标的出现和消失,以及非刚性物体的尺度变化和变形,具有较强的鲁棒性。     

Tracking video objects with feature points based particle filtering

For intelligent video surveillance, the adaptive tracking of multiple moving objects is still an open issue. In this paper, a new multi-object tracking method based on video frames is proposed. A type of particle filtering combined with the SIFT (Scale Invariant Feature Transform) is proposed for motion tracking, where SIFT key points are treated as parts of particles to improve the sample distribution. Then, a queue chain method is adopted to record data associations among different objects, which could improve the detection accuracy and reduce the computational complexity. By actual road tests and comparisons, the system tracks multi-objects with better performance, e.g., real time implementation and robust against mutual occlusions, indicating that it is effective for intelligent video surveillance systems.     

A frame-level encoder rate control scheme for transform domain Wyner-Ziv video coding

Available distributed video coding codecs are mostly based on decoder rate control scheme where the parity bits for decoding can be achieved over a feedback channel. Meanwhile, the frequent requests over feedback channel increase the transmission delay. The feedback-free distributed video coding, relying on encoder rate control in literatures, has overcome the aforementioned shortcoming. However, when performing parity bitrate estimation and other operations, the feedback-free distributed video coding systems based on bit-plane usually require high precision of bitrate estimation and high quality of side information at the encoder. In this paper, we propose a frame-level distributed video coding system based on encoder rate control. The innovations include three parts: 1) an adaptive coding mode selection algorithm is proposed, which utilizes both temporal and spatial correlation and reduces the complexity of encoder; 2) a bit-plane rearrangement method is adopted, which makes the coding rate on each bit-plane homogeneous and effectively reduces the accuracy requirement of the parity bitrate prediction and improves the efficiency of rate estimation; 3) a frame-level parity bitrate estimation scheme is presented to enhance the efficiency of rate estimation on the basis of a look-up table. Numerical results verify that the proposed scheme remarkably improves the rate distortion performance of distributed video coding at low bitrate.     

Adaptive extended Kalman filtering for visual motion estimation of 3D objects

An algorithm for the real-time estimation of the position and orientation of a moving object of known geometry is presented in this paper. An estimation algorithm is adopted where a discrete-time extended Kalman filter computes the object pose on the basis of visual measurements of the object features. The scheme takes advantage of the prediction capability of the extended Kalman filter for the pre-selection of the features to be extracted from the image at each sample time. To enhance the robustness of the algorithm with respect to measurement noise and modelling error, an adaptive version of the extended Kalman filter, customized for visual applications, is proposed. Experimental results on a fixed single-camera visual system are presented to test the performance and the feasibility of the proposed approach.     

结合显著特征与运动目标滤除的动态场景识别

针对存在运动目标的动态环境,提出一种基于动态目标滤除思想的显著特征提取方法,据此实现基于局部图像特征的场景识别。首先简要介绍基于局部显著图像特征的场景识别方法,然后提出了带动态目标滤除思想的显著特征提取框架,并详细讨论了运动目标检测及提取的实现。实验结果和分析表明,该方法能够有效地过滤环境中的运动目标,提高场景识别的精度。     

Exploiting rich user information for one-class collaborative filtering

One-class collaborative filtering (OCCF) is an emerging setup in collaborative filtering in which only positive examples or implicit feedback can be observed. Compared with the traditional collaborative filtering setting where the data have ratings, OCCF is more realistic in many scenarios when no ratings are available. In this paper, we propose to improve OCCF accuracy by exploiting the rich user information that is often naturally available in community-based interactive information systems, including a user’s search query history, and purchasing and browsing activities. We propose two major strategies to incorporate such user information into the OCCF models: One is to linearly combine scores from different sources, and the other is to embed user information into collaborative filtering. Furthermore, we employ the MapReduce framework for similarity computation over millions of users and items. Experimental results on two large-scale retail datasets from a major e-commerce company show that the proposed methods are effective and can improve the performance of the OCCF over baseline methods through leveraging rich user information.     

Exploiting local spatio-temporal characteristics for effective video understanding

Multimedia Tools and Applications - The explosive growth in online video streaming presents challenges for video understanding with high accuracy and low computation complexity. Recent methods have...     

Exploiting multi-expression dependences for implicit multi-emotion video tagging

In this paper, a novel approach of implicit multiple emotional video tagging is proposed, which considers the relations between the users' facial expressions and emotions as well as the relations among multiple expressions. First, the audiences' expressions are inferred through a multi-expression recognition model, which consists of an image-driven expression measurement recognition and a Bayesian network representing the co-existence and mutual exclusion relations among multi-expressions. Second, the videos' multi-emotion tags are obtained from the recognized expressions by another Bayesian Network, capturing the relations between expressions and emotions. Results of the experiments conducted on the JAFFE and NVIE databases demonstrate that the performance of expression recognition is improved by considering the relations among multiple expressions. Furthermore, the relations between expressions and emotions help improve emotional tagging, as our approach outperforms the traditional expression-based or image-driven implicit tagging methods.     

Extracting semantic video objects

We present an accurate and user-interactive semantic video object (SVO) extraction system. Although we also obtain an SVO with an accurate boundary by integrating temporal and spatial information, our way is quite different from others' work. Instead of fusing spatial and temporal segmentations on the first or all the frames of a video sequence, our system adaptively performs spatial and temporal segmentation and fusion when necessary. To achieve this, our system detects the variations between successive frames. We only need to fuse the spatial and temporal segmentation when a large variation occurs. Otherwise, the system tracks the previous SVO's boundary. We find this simple method efficient in both speed and accuracy. Since the temporal segmentation, spatial segmentation, spatio-temporal fusion, and boundary tracking all employ simple algorithms, our system has a low computational complexity     

Detecting video frame rate up-conversion based on frame-level analysis of average texture variation

Multimedia Tools and Applications - Frame rate up-conversion (FRUC) refers to frame interpolation between adjacent video frames to increase the motion continuity of low frame rate video, which can...     

Exploiting user feedback for online filtering in event-based systems

Modern large-scale internet applications represent today a fundamental source of information for millions of users. The larger is the user base, the more difficult it is to control the quality of data that is spread from producers to consumers. This can easily hamper the usability of such systems as the amount of low quality data received by consumers grows uncontrolled. In this paper we propose a novel solution to automatically filter new data injected in event-based systems with the aim of delivering only content consumers are actually interested in. Filtering is executed by profiling producers and consumers, and matching their profiles as new data is produced. Profiles are built by aggregating feedback submitted by consumers on previously received data.     

Exploiting spatial-temporal context for trajectory based action video retrieval

Multimedia Tools and Applications - Retrieving videos with similar actions is an important task with many applications. Yet it is very challenging due to large variations across different videos....     

Shape-based retrieval of video objects

The increasing availability of object-based video content requires new technologies for automatically extracting and matching of the low level features of arbitrarily shaped video. This paper proposes methods for shape retrieval of arbitrarily shaped video objects. Our methods take into account not only the still shape features but also the shape deformations that may occur in an object's lifespan. We compute the shape similarity of video objects by comparing the similarity of their representative temporal instances. We also describe motion of a video object via describing the deformations in an object's shape. Experimental results show that our proposed methods offer very good retrieval performance and match closely with the human ranking.     

一种时空域联合的机动视频目标精确跟踪方法

提出一种采用Bhattacharyya系数最大化并联合时空域信息的视频目标跟踪方法。时域通过卡尔曼滤波预测目标的运动信息,空域用Camshift算法精确匹配视频目标。由于运动目标机动性比较强,卡尔曼滤波预测的位置和真实位置存在较大的误差,容易导致下一步跟踪失败。采用基于Bhattacharyya系数的由粗到精的核匹配搜索方法,在卡尔曼滤波预测的位置基础上适当扩大搜索范围,通过Bhattacharyya系数最大化确定初始匹配窗口,再用Camshift算法精确匹配视频目标。实验证明该方法对机动快速运动目标具有很高的跟踪精度。     

Watermarking of MPEG-4 video objects

The recent finalization of MPEG-4 will make this standard very attractive for a large range of applications such as video editing, Internet video distribution, wireless video communications. Some of these applications are likely to get great benefit from watermarking technology, since it can enable a number of innovative services, such as conditional access policies, data annotation, data labeling, content authentication, to be implemented at a low price. One of the key points of the MPEG-4 standard is the possibility to access and manipulate objects within a video sequence. Thus object watermarking has to be achieved in such a way that, while a video object is transferred from a sequence to another, it is still possible to correctly access the data embedded within the object itself. The algorithm proposed in this paper embeds a watermark in each video object by imposing a particular relationship between some predefined pairs of quantized discrete cosine transform (DCT) coefficients in the luminance blocks of pseudo-randomly selected macroblocks (MBs). Watermarks are equally embedded into intra and inter MBs. Experimental results are presented validating the effectiveness of the proposed approach.     

Redundancy filtering and fusion verification for video copy detection

Multimedia Systems - Recently, the frame fusion based video copy detection scheme provides a possibility to detect copies in a continuous query video stream. However, its computational complexity...     

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.     

Tracking deforming objects using particle filtering for geometric active contours

Tracking deforming objects involves estimating the global motion of the object and its local deformations as a function of time. Tracking algorithms using Kalman filters or particle filters have been proposed for finite dimensional representations of shape, but these are dependent on the chosen parametrization and cannot handle changes in curve topology. Geometric active contours provide a framework which is parametrization independent and allow for changes in topology, in the present work, we formulate a particle filtering algorithm in the geometric active contour framework that can be used for tracking moving and deforming objects. To the best of our knowledge, this is the first attempt to implement an approximate particle filtering algorithm for tracking on a (theoretically) infinite dimensional state space.     

一种自适应的运动目标阴影消除新算法

精确地消除活动阴影对运动目标的影响是智能视频监控的核心任务之一,对此提出了一种基于局部纹理分析的自适应阴影消除新算法。进行了基于高斯混合模型的背景重建,并根据阴影的光学特性进行了阴影区域的预检测,得到疑似阴影区域;提出了一种新的自适应动态纹理分析方法并在此基础上实现了活动阴影的检测与消除。实验结果验证了算法的有效性和实用性。