1. School of Electronic and Optical Engineering, Nanjing University of Science and Technology, 200 Xiao Ling Wei, Nanjing 210094, China
2. Information Technology Research Center, China Electronics Standardization Institute, No. 1 Andingmen East Street, Beijing 100007, China
3. National Key Laboratory for Digital Multimedia Chip Technology, Vimicro Corporation, Beijing 100191, China
4. College of Computer Science & Technology, Zhejiang University of Technology, Hangzhou 310023, China