Research And Application Of Video Background Replacement Technology

Video background replacement refers to the process of extracting foreground from a video sequence and composite it with a new background,it plays an important role in video editing field and has very high application value.Video matting is the main way to realize video background replacement.However,matting has been an under-constraint problem for a long time,it can't be solved appropriately without some constraints.Early methods either fix the background or photograph in a specific environment to help matting,which greatly affect the development of matting technology.So,in order to break through this limitation,many researchers begin to study natural image matting technology,which is much more adaptive in many fields.Video matting,extended from image matting,is limited by its data size.Since most image matting methods require some user interaction,we can't apply them to videos directly.How to reduce the amount of user interaction,how to improve the matting quality and how to speed up the matting process are key points of our current study.In this paper,we focus on the study of existing image and video matting methods,and propose two different methods for video matting.The main work of our study is as follow:1)We propose a video matting approach based on motion estimation.Firstly,trimaps are not required in our method,we select some keyframes and segment them into rough foreground and background.Then,we propagate segmentation results of keyframes to other frames by a motion estimation algorithm based on block matching.Finally,we use the improved guided filter to refine the result of the segmentation sequence and replace the background of original video.2)We propose a video matting approach based on Bayesian estimation and KNN matting.Firstly,we only require the user to provide the alpha of first frame,this work can be done by any image matting method.Then,we use Bayesian estimation to automatically produce the trimap of other frames,and apply KNN matting algorithm to compute the alpha of each frame.Finally,we use the improved guided filter to refine the result,and composite the alpha sequence with a new background.3)We design and realize an interactive background replacement system which contains the basic functions of image and video matting.