Color-based video segmentation using interlinked irregular pyramids

This paper presents a new segmentation technique for video sequences. It relies on building irregular pyramids based on its homogeneity over consecutive frames. Pyramids are interlinked to keep a relationship between the regions in the frames. Virtual nodes are considered to improve matching between low resolution levels of the pyramids. Its performance is good in real-world conditions because it does not depend on image constrains.     

Spatiotemporal video segmentation and motion estimation through irregular pyramids

This paper presents a new spatiotemporal segmentation technique for video sequences. It relies on building irregular pyramids based on its homogeneity over consecutive frames. Pyramids are interlinked to keep a relationship between the regions in the frames. Its performance is good in real-world conditions because it does not depend on image constrains.     

A multiresolution spatiotemporal motion segmentation technique for video sequences based on pyramidal structures

This paper presents a new spatiotemporal segmentation technique for video sequences. It relies on building adaptively interlinked pyramids over consecutive frames. Pyramids are interlinked to keep a relationship between the regions in the frames. Its performance is good in real-world conditions because it does not depend on image constraints.     

基于运动矢量细化的帧率上变换与HEVC结合的视频压缩算法

将帧率变换技术与新型视频压缩编码标准HEVC相结合有利于提升视频的压缩效率。针对直接利用HEVC码流信息中的低帧率视频的运动矢量进行帧率上变换时效果不理想的问题,文中提出了一种基于运动矢量细化的帧率上变换与HEVC结合的视频压缩算法。首先,在编码端对原始视频进行抽帧,降低视频帧率;其次,对低帧率视频进行HEVC编解码;然后,在解码端与从HEVC码流中提取出的运动矢量相结合,利用前向-后向联合运动估计对其进行进一步的细化,使细化后的运动矢量更加接近于对象的真实运动;最后,利用基于运动补偿的帧率上变换技术将视频序列恢复至原始帧率。实验结果表明,与HEVC标准相比,所提算法在同等视频质量下可节省一定的码率。同时,与其他算法相比,在节省码率相同的情况下,所提算法重建视频的PSNR值平均可提升0.5 dB。     

基于混合高斯和帧间差分的机场跑道入侵检测

入侵机场跑道的威胁目标检测,难点在于算法的高精度和实时性.针对传统混合高斯背景差分运动目标检测算法自适应性较差的缺点,提出一种混合高斯背景差分与帧间差分相结合的运动目标检测算法,将帧间差分的结果反馈到混合高斯模型中,实现光线突变时高斯模型快速收敛,再进行图像后处理以获得精准的运动威胁目标.在Matlab仿真平台上进行实验,结果表明,提出的算法兼顾了检测的速度和精度,分别可达l0-1秒级和像素级,满足了入侵机场跑道的威胁目标检测的需求,为机场终端区跑道入侵检测提供了有效的方法.     

Video shot characterization

This paper presents a practical approach to detecting shot cuts and extracting keyframes from video sequences. Shot cut detection has two stages - global motion compensation, followed by an adaptive thresholding algorithm. The motion information is further utilized to extract representative keyframes. Special consideration has been given to achieving real-time performance on a regular PC, which led to a motion estimation algorithm of linear complexity.Received: 1 September 2003, Accepted: 12 March 2004, Published online: 8 June 2004 Correspondence to: Mihai OsianResearch supported by the EC project VIBES     

高速机动目标检测算法研究

研究机载雷达高速机动目标检测问题,指出目标的高机动性带来回波包络走动以及多普勒频率展宽,导致传统相参积累效果下降、检测概率降低.为了解决上述问题,提出了一种随机Hough变换的检测方法,将多脉冲观测时长内的高速机动目标回波能量积累问题转化为图像域的直线与曲线检测问题,使得未知速度、加速度的目标包络走动及弯曲得到积累,实现了匀速和匀加速度运动目标的有效检测,并获得速度与加速度的估计值.仿真结果证明了该方法的有效性.     

基于三阶帧差的运动特征选取方案

为解决行为识别中运动特征提取的问题,该文提出了一种基于三阶帧差的运动特征提取方案,用于提取运动特征中的变化大小、运动变化的一致性、运动方向的一致性等。实验证明,新方法速度快,准确度高。     

基于三阶帧差的运动特征选取方案

为解决行为识别中运动特征提取的问题,该文提出了一种基于三阶帧差的运动特征提取方案,用于提取运动特征中的变化大小、运动变化的一致性、运动方向的一致性等。实验证明,新方法速度快,准确度高。     

Accurate optical flow computation under non-uniform brightness variations

In this paper, we present a very accurate algorithm for computing optical flow with non-uniform brightness variations. The proposed algorithm is based on a generalized dynamic image model (GDIM) in conjunction with a regularization framework to cope with the problem of non-uniform brightness variations. To alleviate flow constraint errors due to image aliasing and noise, we employ a reweighted least-squares method to suppress unreliable flow constraints, thus leading to robust estimation of optical flow. In addition, a dynamic smoothness adjustment scheme is proposed to efficiently suppress the smoothness constraint in the vicinity of the motion and brightness variation discontinuities, thereby preserving motion boundaries. We also employ a constraint refinement scheme, which aims at reducing the approximation errors in the first-order differential flow equation, to refine the optical flow estimation especially for large image motions. To efficiently minimize the resulting energy function for optical flow computation, we utilize an incomplete Cholesky preconditioned conjugate gradient algorithm to solve the large linear system. Experimental results on some synthetic and real image sequences show that the proposed algorithm compares favorably to most existing techniques reported in literature in terms of accuracy in optical flow computation with 100% density.     

3D head tracking under partial occlusion

A new algorithm for 3D head tracking under partial occlusion from 2D monocular image sequences is proposed. The extended superquadric (ESQ) is used to generate a geometric 3D face model in order to reduce the shape ambiguity during tracking. Optical flow is then regularized by this model to estimate the 3D rigid motion. To deal with occlusion, a new motion segmentation algorithm using motion residual error analysis is developed. The occluded areas are successfully detected and discarded as noise. Furthermore, accumulation error is heavily reduced by a new post-regularization process based on edge flow. This makes the algorithm more stable over long image sequences. The algorithm is applied to both synthetic occlusion sequence and real image sequences. Comparisons with the ground truth indicate that our method is effective and is not sensitive to occlusion during head tracking.     

极低码率视频编码中块自适应分割运动估值

在极低码率视频编码运动估值过程中,针对视频对象的边缘形状特征,将宏块按不同形状的模板自适应地进行分割,同时引入近期、远期２个参考帧进行块匹配。为提高搜索速度,首先判断出不需编码的宏块,并引用了一种快速搜索算法。实验结果表明,与Ｈ．２６３先进预测模式相比,采用所建议的运动补偿方法,图象的信嗓比得到明显的提高。     

Segmenting Traffic Scenes from Grey Level and Motion Information

This paper is concerned with an efficient estimation and segmentation of 2D motion from image sequences, with the focus on traffic monitoring applications. In order to reduce the computational load to achieve real-time implementation, the proposed approach makes use of simplifying assumptions that the camera is stationary, and that the projection of vehicles motion on the image plane can be approximated by translation. We show that satisfactory results can be achieved even under such apparently restrictive assumptions. The use of 2D motion analysis and the pre-segmentation stage significantly reduces the computational load, and the region-based motion estimator gives robustness to noise and changes in the illumination conditions.     

基于感兴趣区域的运动分割算法

提出了一种基于感兴趣区域ROI(Region Of Interests)进行形态学处理的运动分割算法。首先对变化检测得到的二值图像进行分割(粗分割),然后对粗分割后的每个区域内部进行形态学处理,最后再次对经过处理后的二值图像进行分割(细分割)。该算法能够很好地处理噪声较大情况下的运动分割,避免了大面积噪声对于前景目标分割的影响。     

数字图像稳像算法研究

介绍了数字图像稳像算法的整个流程,包括三部分:运动估计、运动决定和运动补偿.重点介绍了运动估计算法和运动补偿中的滤波算法;详细阐述了几种最基本的运动估计算法,其它的运动估计算法可以通过这些基本算法延伸发展得到;列出了三种常用的滤波算法:中值滤波、kalman滤波和二次B样条曲线法,应用于不同的场合;提出了两种方法:裁减和拼接,用来解决当前帧补偿后出现的空白区域问题.最后,展示了一种基于投影估计和kalman滤波的稳像算法的试验结果.通过这些方法的介绍,可以对稳像算法有更直观的了解,探讨了进一步研究的重点.     

Motion estimation based on multiple local constraints and nonlinear smoothing

A new algorithm for estimating motion from image sequences is presented. Initial motion estimates are determined based on a least-squares solution to a set of independent linear constraints on the motion at a pixel. These initial estimates are then improved by a nonlinear smoothing operation. The results of this algorithm are compared with those obtained by the Horn-Schunck algorithm on a number of image sequences.     

运动估值中的最优程序技术

由于运动估值算法的特殊性,程序实现技术对匹配速度有很大影响。通过对基于块匹配法的全匹配算法的具体分析和对一般Ｃ／Ｃ＋＋语言实现方法的改进,给出了在运动估值中可以普遍采用的最优程序技术。文中给出了全匹配算法和典型快速算法的速度与精度以及改进前后的对比实验结果。     

The input-interface of Webcam applied in 3D virtual reality systems

Our research explores a virtual reality application based on Web camera (Webcam) input-interface. The interface can replace with the mouse to control direction intention of a user by the method of frame difference. We divide a frame into nine grids from Webcam and make use of the background registration to compute the moving object. In order to make this technology apply to 3D virtual reality system, we use the Virtools Dev to build virtual scenes and the Microsoft Visual C++ to build this interface. We also use the MySQL database management system to access users’ data and the displaying data. We implement a number of Building Blocks (BB) to support Virtools Dev for using the database management system and the Webcam input-interface in this composite system. The results of research are expected to the digital content industries such that users can easy to use the input-interface to control browsing the virtual reality. Our system can supply interactive digital content, photographs, and access the questions from the database management system. In addition, the system provides the browsing mold, the question mold, and the course content describing mold with the input-interface. In order to explore the intention of users for using the system, we design the questionnaire based on the technology acceptance model (TAM). In our empirical study, we find that perceived playfulness is positive association with attitude toward using. Interface style is positive association with perceived ease of use.