| Studies on three-dimensional (3D) vision are recently becoming increasingly popular due to advances in the 3D display technologies. In soon future, 3D video signal will be important contents of multimedia communication. As the most important 3D display technology, multi-view video has been widely used in the fields of 3D TV, free-viewpoint TV, immersive videoconferencing, virtual reality etc. However, its huge volumn of data is one major obstacle for the application of multi-view video. A multi-fold increase in bandwidth over the existing single-view makes it extremely tough to transmit and store multi-view video data. This thesis mainly concerns the problems of highly efficient multi-view video coding (MVC). To achieve high compression efficiency, correlation among different views must be exploited in multi-view video coding scheme. To this end, several efficient encoding schemes have been proposed in this paper.Firstly, an H.264-based multi-view video coding scheme is introduced. It uses the advanced predictive method of H.264 to eliminate the spatial, temporal and inter-view correlation in multi-view video. According to the characteristic of multi-view video, global disparity coding method is employed. Based on an eight-parameter global disparity model, two global disparity coding schemes are proposed. To decrease the bit rate of motion vector (MV) and disparity vector (DV), an optimized MV and DV predicted method is proposed. It utilizes not only the correlation of neighboring blocks, but also that of corresponding blocks in the adjacent images.Due to the parameter scatterance of cameras, there exists serious color-fluctuation (including brightness variation) among different views. This fluctuation will degrade the compression performance. To improve the coding efficiency of MVC, the method of color-fluctuation compensation is investigated. Firstly , color-fluctuation is analyzed based on the image formation theory. Then, several color-fluctuation compensation methods are proposed according to the simplified models. They are global linear color-variation compensation, global non-linear color-variation compensation, local color-variation compensation and global-local-adaptive color-variation compensation. Experiment results have shown these methods can greatly improve the performance of disparity prediction and the coding efficiency of MVC.Finally, object-based stereo and multi-view video technologies are discussed. An efficient algorithm for disparity matching is presented. Then, disparity field and high-order statistics based stereo video object segmentation method is proposed. Finally, an object based stereo video coder is implemented. Performance of object-based encoder verifies the validity of our algorithm. |
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