The Convenience Of Image And Video Matting Technology Research

Matting is an important operation in image and video processing. With the development of digital technology, matting is widely applied to medical diagnosis, special visual effects and home entertainment. To build priors, traditional digital matting approaches require the user to supply a hint image that partitions the input image into three regions: "foreground", "background", and "unknown" with the background and foreground regions having been delineated conservatively. The hint image is called as trimap. To generate good mattes, all these approaches require the user to "carefully" specify the trimap. However, it requires a considerable degree of user interaction to construct a "good" trimap for an experienced user, and it is almost impossible to manually create an optimal trimap. When images contain large portions of semi-transparent foregrounds or partial pixel coverage, such as the spider web image, manually creating a trimap is a very tedious process. Moreover, it is unimaginable for a video sequences to manually construct trimaps on a per-frame basis.In this dissertation, we focus on the convenient and fast image and video matting techniques and orient them to the domain of special visual effects and home entertainment, etc.. The techniques not only can simplify the user interaction, but also can extract high-qualified matte and foreground. Therefore, we have explored the following problems. First, we research how to create a convenient interactive mode to reduce user's efforts from the tedious process of constructing trimap. Secondly, we explore a local matting technique to allow the user to further improve results locally. Finally, we seek a video matting technique to quickly extract moving mattes and foreground from a great deal of video data. More importantly, the technique explores how to preserve spatio-temporal coherence.Based on the above objectives, the main contents of this dissertation as follows:Chapter 1 introduces the significance of image and video matting, and de- scribes the evolution and development of matting techniques. Subsequently, we reveal the difficulties of image and video matting, elicit the research objectives and the organizations of this dissertation.Chapter 2 presents a stroke-based Easy matting system. We propose an iterative energy minimization framework for interactive image matting and extract high-qualified matte and foreground object. The energy optimization can be further performed in selected local regions for refined results. Due to the existing Dirichlet boundary condition, the modified local regions can be seamlessly integrated into the final results.Chapter 3 extents the Easy matting to video domain, proposes a Markov Chain based approach for video matting. We partition the video sequences into a series of frame-pair containing inter-frame correlation, and construct 3D energy function to optimize each frame-pair. Only few strokes are required to be assigned in few key frames, our system can automatically extract video mattes. And the final results preserve local temporal coherence.Chapter 4 presents an interactive video matting approach that combines the stroke-based interactive mode with video-cubic editing interface; proposes a new volume expansion scheme and a novel automatic background estimation algorithm. The 3D energy optimization framework regards the zero-order continuity and the first-order continuity of matte as a priori expectations, obtains globally optimal solutions. Most importantly, we reconstruct global spatio-temporal mattes and foreground.Finally, Chapter 5 concludes this dissertation by summarizing our contributions and suggesting future research directions.