Study On Image Representation Method Based On Triangular Mesh

Image representation is an important issue is computer graphics, image processing, pattern recognition. Based on computational geometry of the triangle, triangular mesh represention model of image is efficient to represent image, which has great use in video communication, three dimentional reconstruction and so on.With respect to the triangular method in computational geometry, three triangulation approaches of image are proposed.Referring to the idea of contour extraction, characteristic points of image border can be extracted by use of Soble operator, Denauley triangular mesh can be initialized with improved Lawson algorithm .Compared with quadtree and FAACA approaches, the number of characteristic points of CPBT approach decreases by 13.6% and 14.5% respectively. The noise ratio of reconstructed image is lese than FAACA and more then quadtree.Considerd with the partition of area, an image can be divided into a number of polygonal regions, and then each polygon carry can be triangulated, thus an image is represented by a triangular mesh. Compared with CPBT approach, the numbers of vertex of PPBT goes down 5%-13% and the noise ration(PSNR) increases 2%~8%.With respect to the distributing of gray scale, first of all, the image is divided to rectangles with multi-stage wavelet transform. Each rectangle can be to respresented by four initiail regular triangle templates. Then the trianguation partition can be transformed into initial triangulate mesh. The initial triangulate mesh can be divided ulteriorly. The experiment indicates that the size of triangulate mesh is a little larger than WBT, but its complexity is less than WBT distinctly. In addition, regular rectangle block can be in favor of space refinement and parallel computation.A technique on refinement of original triangular mesh which apply to the above three methods is devised. This algorithm considers both small errors and homogenization errors of gray scale on the initial of grid. That is, if the maximum absolute error is less than or equal to pre-given gate threshold, the iteration will stop; Otherwise, the maximum absolute error location is priority to the new iteration. Two basic methods of triangular mesh storage and advanced a data structure are introduced, which records sparse grids and generated rules, and made a good compression results. This method records the spare grid and sub-point sequence formed by initial triangular mesh. In the reconstruction we can get refinement triangular mesh data from generating rules and by plane interpolated methods.The experiments shows that the compress ratio of refinement approach is 4.5 times and 2-4 times to original approach and original image respectively. The noise ratio(PSNR) of reconstructed image is 35. It is obvious that the approach can reduce storage space effiently.Based on the optimized storage approach, the continious frames are analyzed, then a compress method of multi-frame is proposed. The experiment result indicates that the compress ratio of contimuious 8 frames can be 3. Considered with the initial triangular mesh, the compress ratio can increase to 14. The result can prove that the multi-frame compress algorithm has good applicated foreground.A method of image reconstruction by plane interpolation is put forward. This method used the gray value of the triangle vertices to automatically calculate the gray value at any point within it and significantly shows better results than that all the points inside have the same gray value.Based on the image of triangular mesh, with the human face for the study object,the research of three-dimensional reconstruction is touched upon.From the theoretical analysis and the experimental results, the image represention model based on triangular mesh is capable of supporting image represention,three dimentional reconstruction and video compression.