Due to the development of streaming media and emerging of content based functionalities in MPEG 4

object based segmentation technology becomes a popular research in video field. Video segmentation provides an easy and efficient way for video retrieval and coding

whereas it is a difficulty issue in computer vision. From shot based to extraction of video object planes (VOPs)

video segmentation develops to extract video object(VO). In fact

shot based segmentation is one of the primary steps in the true object based video segmentation. Currently

segmentation technology for content based representation is still premature. This article gives an overview of existing techniques for object based segmentation. The performance

relative merits and limitations of each of the approaches are comprehensively discussed and contrasted. Different from the traditional classification approaches

this paper presents a new view of analyzing the recent research in this area. Some important and advanced video segmentation algorithms are analyzed and compared both in theory and experimental results. According to different information used in those algorithms

they are classified into several classes. This classification criterion is more revelatory and useful to developing new segmentation algorithm. Finally

some existing problems worth discussing and directions need to further research are proposed.