基于频域和时域分割的视频对象提取方法研究

【作者】 杨卫；

【导师】 刘钊；

【作者基本信息】 电子科技大学 ， 信号与信息处理， 2003， 硕士

【摘要】 视频对象的提取是任何基于视频对象的操作如索引、访问等的最基本的步骤。本文提出了一种自动地在频域上提取目标轮廓、在时域上提取运动矢量并结合两者信息的对象提取方法。对三维运动模型、图像的小波变换和光流场的分析等，都作了较为深入的研究和探讨。第一章首先介绍了本论文的课题背景及目前多媒体发展的趋势，说明在图像序列中提取视频对象的必要性。接着简要地介绍了当前国内外研究方法及其各自的优缺点，最后提出自己的一套较好的在编解码应用的场合下提取视频对象的方法。第二章对本文适用的视频对象模型进行定义及相关说明，并简要介绍了系统的框图，整个算法从频域和时域这两条主线走，然后联合两者的信息提取最终的视频对象。第三章集中阐述在频域上提取视频对象信息的算法。先介绍图像小波分解方法的原理、Mallat快速算法、多尺度特性、3阶B-样条小波基函数的选取及其滤波器系数的推导等，然后根据小波变换结果计算梯度矢量矩阵，进行非极大值抑制和双阈值化，提取目标轮廓。最后用与经典的canny边缘检测方法进行比较。在第四章中详细介绍了在时域上提取视频对象运动信息的方法。首先构建三维刚体运动的模型，提出一种计算模型的全局运动矢量的方法，并进行全局运动补偿、变化检测模板提取和连通域标记等步骤，然后引入光流场的概念，并介绍其计算原理和方法，用Horn-Schunck迭代法计算图像中各点的局部运动矢量，并据此对变化检测模板的结果进一步提取，获得时域上分割的信息。第五章在前两章的基础上，提出一种邻域相似程度的判据来联合频域、时域分割结果提取对象轮廓，最后进行区域生长、数学形态学算子滤波等后期处理获得最终的视频对象。第六章用多种标准图像序列测试本文所提出的算法并作相应评价。最后一章第七章进行全文总结，并提出改进的方向。更多还原

【Abstract】 Visual objects (VOs) abstraction is the basic step for all kinds of operation, such as index, accessing, which are based on VOs. This paper brings forward an automatic and efficient method of abstracting VOs. Information of both contour of object based on spacial segmentation and motion vector based on temporal segmentation is integrated to get the final VOs. We have introduced and discussed 3D object motion modal, wavelet transform on graphic, optical flow field, and etc.In chapter 1, we first introduce the background of this thesis and the future direction of multi-media development in order to demonstrate the importance of VO abstraction. Then we present current methods in the world in brief, and point out the merits and demerits of every method. At last we put forward an efficient method that is fitted for that work.In chapter 2, we define the modal of VOs and confine the available applied field. Then we introduce in brief the whole frame and the algorithm that integrates the information of both temporal and spacial segmentation.In chapter 3, we expatiate upon the algorithm that abstracts information of VOs based on spacial segmentation. First we introduce theory and merits of graphic wavelet transform, then Mallat algorithm, multi-scale characteristic, quadratic B-alpine wavelet and the coefficients of this filters, and etc. Later we calculate the gradient matrix based on the result of wavelet transform, thin the contour and get spatical information. At the end of this chapter, we compare it with other method, such as canny filter.In chapter 4, we discuss the method of VOs abstraction based on temporal segmentation in detail. First we put forward affine modal, which is a kind of 3-D motion modal of rigid body, compensate global motion vector based on this modal, and get the changed detection mask (CDM). Then we introduce the conception of optical flow field, compute the local<WP=5>motion vector with Horn-Schunck method, and abstract the essential information in temporal field. In chapter 5, we integrate the information got in chapter 3 & 4 with a criterion of adjacent comparability, then use last operations including seed growing, morphological filters, and etc, to get the final VOs from video sequence. We compare this algorithm of integration with other related algorithms in end of this chapter.In chapter 6, we test this whole algorithm with four sets of standard video sequences of MPEG-4, and comment on the result.In the last chapter, chapter 7, we summarize this paper and bring out the direction of improvement.更多还原