【作者】 王养利；

【导师】 吴成柯；

【作者基本信息】 西安电子科技大学 ， 信号与信息处理， 1999， 博士

【摘要】 本文介绍作者在图像表述及视频编码中的几何约束两个方面的研究工作及主要研究成果： 首先，本文提出了一种基于V氏图的图像分割方法。该方法利用V氏图由其种子点位置所唯一确定的性质，通过V氏图种子点来有效表示区域的形状。同时，在该方法中所设计的一个优化过程，使得V氏图区域的边界能够更好地吻合图像中的轮廓；在所提出的图像的V氏图分割方法的基础上，本文研究了表述V氏图区域内图像内容的方法，进一步提出了一种图像的V氏图表述方法。 然后，本文研究了三角形区域内的自适应DCT变换，提出了一种结合DT分割及自适应DCT的图像编码方法。该方法用对任意三角形内的两次一维DCT对DT分割和编码后的误差信号进行变换编码，并依据每一三角形内误差信号的统计特性，自适应地调整一维DCT的方向以提高变换效率。这种结合DT分割及自适应DCT的图像编码方法充分利用了基于图像内容的DT分割及正交变换编码的优点，可以获得较好的恢复图像质量。 最后，本文从视频编码的角度研究了序列图像间的几何约束，主要是序列中两幅图像之间的对极几何约束和三幅图像之间的三线性约束。提出了一种在对极几何约束下来求取三角形网格结点位移的方法。该方法将确定网格结点位移矢量的问题转化为在对极几何约束下求取两帧之间网格结点的对应关系问题。在降低运算量的同时，得到较为精确的网格结点位移估计。本文还提出了一种结合三焦张量和BMA的运动估计方法。在有相机平移及景物有深度变化时，该方法的运动补偿效果明显好于单纯BMA方法；更多还原

【Abstract】 Researches on image representation and on applications of geometric constraints in video coding are presented in this paper. Main contributions are as follows: Firstly, an image segmentation method based on Voronoi diagrams is proposed, which utilizes the promising property of Voronoi diagrams, i.e., the shape of a Voronoi region can be determined by the position of its seed, and represents the shape of a Voronoi region by its seed. In addition, an optimization procedure designed in the approach can make edges of a Voronoi region run parallel to image contours. On the basis of the approach, some methods suitable for image content representation within a Voronoi region are further studied and an image representation scheme based on Voronoi diagrams is proposed. Then, triangle oriented shape adaptive DCI is studied and an image coding method based on Delaunay triangulation and adaptive DCT is presented. In this approach, residual signals, which are produced by segmentation and coding based on Delaunay triangulation, are encoded by conducting one-dimensional DCT twice within each triangle. By adaptively adjusting directions of the one dimensional DCT according to statistics of the residual signals, transform efficiency can be further improved. The approach has taken full advantage of image content oriented Delaunay triangulation and transform coding, and has improved the quality of reconstructed images. Finally, geometrical constraints in image sequences, mainly including Epipolar geometry and Trilinear constraint, are studied from the view of video coding. A method to determine mesh node displacement using Epipolar geometry is proposed. By converting the problem of determining mesh node displacement to that of determining corresponding relation between two frames under the constraint of Epipolar geometry, the approach has reduced computational cost and still gives comparatively precise mesh node motion estimation. A motion estimation method based on Trifocal tensor and BMA is also proposed, which gives much better motion compensation results compared with BMA when there are camera translation and scene depth variation.更多还原