基于边缘前景的混合高斯模型目标检测

混合高斯模型已经广泛应用于背景建模中。但是检测结果受到噪音的干扰和突变光照的影响。为了解决这个问题,将Stauffer的混合高斯模型进行改进并与边缘信息相结合。当三帧差分判断出场景变化时,像素点的学习率会自适应变化。用这种改进的混合高斯模型来获取运动物体的边缘图像和前景图像。对边缘图像进行图像膨胀,再与前景图像进行与运算,通过光流信息来填补空洞部分,得到最后的结果。实验结果表明,可以很好地去除噪音和解决光照突变的影响,提高了目标检测的效果,比传统方法更加有效。     

A fuzzy spatial coherence-based approach to background/foreground separation for moving object detection

The detection of moving objects from stationary cameras is usually approached by background subtraction, i.e. by constructing and maintaining an up-to-date model of the background and detecting moving objects as those that deviate from such a model. We adopt a previously proposed approach to background subtraction based on self-organization through artificial neural networks, that has been shown to well cope with several of the well known issues for background maintenance. Here, we propose a spatial coherence variant to such approach to enhance robustness against false detections and formulate a fuzzy model to deal with decision problems typically arising when crisp settings are involved. We show through experimental results and comparisons that higher accuracy values can be reached for color video sequences that represent typical situations critical for moving object detection.     

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。     

Joint fuzzy background and adaptive foreground model for moving target detection

Moving target detection is one of the most basic tasks in computer vision. In conventional wisdom, the problem is solved by iterative optimization under either Matrix Decomposition (MD) or Matrix Factorization (MF) framework. MD utilizes foreground information to facilitate background recovery. MF uses noise-based weights to fine-tune the background. So both noise and foreground information contribute to the recovery of the background. To jointly exploit their advantages, inspired by two framework complementary characteristics, we propose to simultaneously exploit the advantages of these two optimizing approaches in a unified framework called Joint Matrix Decomposition and Factorization (JMDF). To improve background extraction, a fuzzy factorization is designed. The fuzzy membership of the background/foreground association is calculated during the factorization process to distinguish their contributions of both to background estimation. To describe the spatio-temporal continuity of foreground more accurately, we propose to incorporate the first order temporal difference into the group sparsity constraint adaptively. The temporal constraint is adjusted adaptively. Both foreground and the background are jointly estimated through an effective alternate optimization process, and the noise can be modeled with the specific probability distribution. The experimental results of vast real videos illustrate the effectiveness of our method. Compared with the current state-of-the-art technology, our method can usually form the clearer background and extract the more accurate foreground. Anti-noise experiments show the noise robustness of our method.     

利用时空背景模型的快速运动目标检测方法

为了弥补运动目标检测中传统混合高斯背景模型仅对单个像素建模、运算耗时的不足,通过提取背景时间统计特征和空间区域特征建立模型,针对模型中的高斯分量采用一种改进的分量个数自适应算法,并在此模型基础上,提出一种自适应迭代分块目标检测方法。通过包含区域信息的背景模型检测目标,减少在同一背景区域中目标的误判和漏判。将自适应迭代分块检测算法与背景的区域信息结合,可以在不降低检测精度的前提下大大提高算法执行速度。实验结果表明,相对于传统算法,本文检测法检测结果信噪比更高,目标更加完整,运行速度平均提高了22%。     

Accelerated hardware video object segmentation: From foreground detection to connected components labelling

This paper demonstrates the use of a single-chip FPGA for the segmentation of moving objects in a video sequence. The system maintains highly accurate background models, and integrates the detection of foreground pixels with the labelling of objects using a connected components algorithm. The background models are based on 24-bit RGB values and 8-bit gray scale intensity values. A multimodal background differencing algorithm is presented, using a single FPGA chip and four blocks of RAM. The real-time connected component labelling algorithm, also designed for FPGA implementation, run-length encodes the output of the background subtraction, and performs connected component analysis on this representation. The run-length encoding, together with other parts of the algorithm, is performed in parallel; sequential operations are minimized as the number of run-lengths are typically less than the number of pixels. The two algorithms are pipelined together for maximum efficiency.     

Detection of moving foreground objects in videos with strong camera motion

In this paper, we propose a novel method for moving foreground object extraction in sequences taken by a wearable camera, with strong motion. We use camera motion compensated frame differencing, enhanced with a novel kernel-based estimation of the probability density function of background pixels. The probability density functions are used for filtering false foreground pixels on the motion compensated difference frame. The estimation is based on a limited number of measurements; therefore, we introduce a special, spatio-temporal sample point selection and an adaptive thresholding method to deal with this challenge. Foreground objects are built with the DBSCAN algorithm from detected foreground pixels.     

改进的基于混合高斯模型的运动目标检测算法

针对传统混合高斯模型检测运动目标中存在的不足,提出了一种改进的基于混合高斯模型的运动目标检测算法。将改进的混合高斯模型与四帧差分相结合,有效地解决了突变光照的影响并消除了传统帧差法检测目标时容易出现的双影现象,改进的混合高斯模型自适应地调整了高斯模型的分布数量,提高了背景的描述精度。分情况讨论了物体的运动状态并分别设置不同的学习率,改善了对运动缓慢目标的检测效果。实验结果表明结合后的算法能对运动目标进行准确检测,对复杂场景有较好的适应性。     

基于时空背景模型的自适应运动目标检测方法

现有的视觉背景提取方法(ViBe)在背景建模时只利用了像素的空间信息,而忽略时间信息,降低了检测的准确性,且检测半径和背景更新的随机子采样因子都为固定常数,在动态背景干扰、相机抖动等情况下,检测效果不理想。针对这些问题,提出一种时空背景模型的自适应运动目标检测方法。首先,在ViBe方法中加入时间信息建立时空背景模型;然后,在检测和更新过程中,提出背景模型中样本的标准差能反映背景的复杂度,通过计算样本的标准差来自适应地改变检测半径和背景更新的随机子采样因子适应背景的变化。实验结果表明,改进的方法不仅能够在静态背景和光照均匀的情况下有效地检测出前景像素,而且对存在光线变化较大、相机抖动、动态背景干扰等情况也有一定的抑制作用,提高了检测的准确性。     

基于改进混合高斯模型的运动物体检测研究

针对传统高斯建模的初始化问题、参数值的计算依赖于先前所有帧和零散噪点较多等问题,提出了一种改进混合高斯模型的方法,即在初始化每个像素点时采用邻域特性和中值滤波相结合的方法,用来获取更接近实际的初始背景。同时对背景模型的更新提出了改进方法,在原有的背景排序基础上增加“定时清零”策略,使新加入的像素点能快速匹配。最后对特定区域的学习速率进行重新设定,再结合像素点的空间分布特性,达到消除零散噪点和部分空洞的目的。实验结果表明,与传统的混合高斯模型相比,本文算法能准确的检测出运动物体,并对阴影和噪音有一定的抑制作用。     

贝叶斯理论在移动目标检测中的应用

复杂背景下精准的移动目标检测是智能监控系统的重要任务之一,而移动目标检测中,阈值的选择是关键因素之一。传统的固定阈值检测算法很难满足光照等复杂环境的实际需要,利用贝叶斯理论,提出了自适应的动态阈值移动目标检测算法,通过引入前景图像的均值和方差,以及背景图像的均值,获得自适应的动态阈值,用于克服光照等复杂条件的不利影响。实验结果显示,同传统的固定阈值检测算法相比,提出的算法可以有效地克服噪声的影响,并且在复杂环境下具有更好的鲁棒性和稳定性。     

摄像机旋转运动下的快速目标检测算法

论文提出了一种摄像机旋转运动下的快速目标检测算法。首先为图像的全 局运动建立旋转参数模型,然后基于运动预测在相邻帧之间建立SIFT 特征点对,利用 RANSAC 去除外点的影响,结合最小二乘法求解全局运动参数进行运动补偿,基于残差图 像的更新策略实时更新特征点集,以适应背景的变化,最后使用帧差法获得运动目标。该算 法不仅保持了SIFT 本身的优越性能,而且极大地提高了检测速度。实验结果表明该算法可 以实时准确的检测出运动目标。     

轮廓随机序列模型及其分级检测技术*

研究了运动目标图像随机轮廓模型,它包含四特征模型和三参数非平稳随机序列描述,进而拟订了轮廓检测定理;然后建立了轮廓分级检测系统,根据轮廓分割了目标图像.系统包含二阶时差分变换、全域自学习的高信噪比轮廓点二元聚类检测;中信噪比轮廓点自学习的局域检测;在时空域基于封闭和Markov关联准则的低信噪比轮廓点检测.实验仿真给出了良好的结果.     

Qualitative detection of motion by a moving observer

Two complementary methods for the detection of moving objects by a moving observer are described. The first is based on the fact that, in a rigid environment, the projected velocity at any point in the image is constrained to lie on a 1-D locus in velocity space whose parameters depend only on the observer motion. If the observer motion is known, an independently moving object can, in principle, be detected because its projected velocity is unlikely to fall on this locus. We show how this principle can be adapted to use partial information about the motion field and observer motion that can be rapidly computed from real image sequences. The second method utilizes the fact that the apparent motion of a fixed point due to smooth observer motion changes slowly, while the apparent motion of many moving objects such as animals or maneuvering vehicles may change rapidly. The motion field at a given time can thus be used to place constraints on the future motion field which, if violated, indicate the presence of an autonomously maneuvering object. In both cases, the qualitative nature of the constraints allows the methods to be used with the inexact motion information typically available from real-image sequences. Implementations of the methods that run in real time on a parallel pipelined image processing system are described.     

Real-time velocity measurement to linear motion of a rigid object with monocular image sequence analyses

This paper presents a methodology and all procedures used to validate it, which were executed in a physics laboratory under controlled and known conditions. The validation was based on the analyses of registered data in an image sequence and the measurements acquired by high precision sensors. This methodology intended to measure the velocity of a rigid object in linear motion with the use of an image sequence acquired by commercial digital video camera. The proposed methodology does not need a stereo pair of images to calculate the object position in the 3D space: it needs only images sequence acquired for one, only one, angle view (monocular vision). To do so, these objects need to be detected while in movement, which is conducted by the application of a segmentation technique based on the temporal average values of each pixel registered in N consecutive image frames. After detecting and framing these objects, specific points belonging to the object (pixels), on the plane image (2D coordinates or space image), are automatically chosen, which are then transformed into corresponding points in the space object (3D coordinates) by the application of collinearity equations or rational functions (proposed in this work). After obtaining the coordinates of these points in the space object that are registered in the sequence of images, the distance, in meters, covered by the object in a particular time interval may be measured and, consequently, its velocity can be calculated. The system is low cost, use only a computer (architecture Intel I3), and a webcam used to acquire the images (640 × 480, 30 fps). The complexity of the algorithm is linear, fact that allows the system to operate in real time. The results of the analyses are discussed and the advantages and disadvantages of the method are presented.     

New trends on moving object detection in video images captured by a moving camera: A survey

This paper presents a survey on the latest methods of moving object detection in video sequences captured by a moving camera. Although many researches and excellent works have reviewed the methods of object detection and background subtraction for a fixed camera, there is no survey which presents a complete review of the existing different methods in the case of moving camera. Most methods in this field can be classified into four categories; modeling based background subtraction, trajectory classification, low rank and sparse matrix decomposition, and object tracking. We discuss in details each category and present the main methods which proposed improvements in the general concept of the techniques. We also present challenges and main concerns in this field as well as performance metrics and some benchmark databases available to evaluate the performance of different moving object detection algorithms.     

动态背景下空时特性均显著的运动目标检测

从序列图像中提取变化区域是运动检测的主要作用,动态背景的干扰严重影响检测结果,使得有效性运动检测成为一项困难工作。受静态图像显著性检测启发,提出了一种新的运动目标检测方法,采用自底向上与自顶向下的视觉计算模型相结合的方式获取图像的空时显著性：先检测出视频序列中的空间显著性,在其基础上加入时间维度,利用改进的三帧差分算法获取具有运动目标的时间显著性,将显著性目标的检测视角由静态图像转换为空时性均显著的运动目标。实验和分析结果表明：新方法在摄像机晃动等动态背景中能较准确检测出空时均显著的运动目标,具有较高的鲁棒性。     

Correction to: Salient object detection using the phase information and object model

Multimedia Tools and Applications - The article Salient object detection using the phase information and object model, written by Hooman Afsharirad and Seyed Alireza Seyedin, was originally...     

运动目标检测中的环境感知与自适应研究

在复杂环境下,任何环境的改变都会对运动目标检测的准确性产生影响。因此提出广义高斯混合模型与背景减除法相结合的算法对运动目标进行检测。该模型可以灵活地感知环境,自适应地处理视频背景模型中背景的环境变化,如光线渐变、背景扰动、阴影和噪声等,而且当光线突变时可以迅速感知并重新建模。此外为了满足实时性,采取每隔3帧进行一次背景更新的策略。实验结果证明本算法在满足实时性的同时,能准确检测出运动目标。