Algorithm and Architecture Study on Disparity Map Synthesis for Light-Field Viewpoint Synthesis

• Main Authors: Cheng, Wei Han, 程韋翰
• Other Authors: Huang, Chao Tsung
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/vvt3zs

碩士 === 國立清華大學 === 電機工程學系 === 105 === The applications of light field camera have gradually become the mainstream research in computational photography, and free viewpoint synthesis has become a hot spot in the research. Free viewpoint synthesis can synthesize any viewpoints which are required from light field camera. In recent years, the related research of free viewpoint synthesis of DIBR (depth-image-based rendering) has revealed that the number of disparity maps is as same as the number of viewpoints in the light field configuration. If these disparity maps are all from disparity search algorithm or sensor, the algorithm complexity and the hardware costs are too high. Therefore, it is important to synthesize good quality of viewpoint by using less disparity maps. This thesis emphasizes the use of only one disparity map to complete free viewpoint synthesis in light field configuration. We find out that DIBR algorithm still needs another corresponding disparity map, so we forward warp the disparity map we already have to the corresponding viewpoint. However, holes appear after forward warping, and they affect the quality of viewpoint synthesis. Holes must be filled in order to synthesize viewpoint afterwards. Therefore, how to fill holes and achieve good quality are critical. In addition, hole filling algorithm is also the bottleneck in our system, so we design hardware architecture to reach real-time computation. We divide hole filling into two aspects: algorithm and architecture. In algorithm, we use weighted mode filter(WMF) to fill holes, but general WMF makes foreground information spread and requires high complexity. Our proposed method optimizes the quality of hole filling and reduce computational complexity. In hardware, the size of SRAM is proportional to the number of disparity labels in traditional hardware architecture of WMF. Therefore, we propose the algorithm and architecture of cacheable histogram to WMF. Proposed method can reduce the size of SRAM and hardware area. Our proposed algorithm can complete 2D free viewpoint synthesis by using only one disparity map. We also propose hardware architecture and algorithm to make hardware area smaller than traditional WMF architecture. In the high resolution light field which has 256 disparity labels, our hardware area is only 14% of traditional hardware of WMF, but our method can still reach similar quality of disparity map and synthesized viewpoint.