Natural Image and Video Matting

The process of extracting a foreground object from an image based on limited user input, is an important task in image and video editing. This paper addresses the problem of efficient extraction of a foreground object in a complex environment whose background cannot be trivially subtracted. Natural image matting is usually composed of: foreground and background color estimating and alpha estimating. Current approaches either restrict the estimation to a small part of the image, i.e. estimate foreground and background colors based on nearby pixels where they are known, or perform iterative nonlinear estimation by alternating foreground and background color estimation with alpha estimation. This paper presents an object extraction technique which uses global color and local smoothness information to estimate the accurate alpha values. We then extend the object extraction method to video, where from a single video shot with a moving foreground object and stationary background, the motion statistics, color and contrast cues are combined to extract a foreground object efficiently with no interaction from the user.