1. Department of Computer Science, Huaqiao University, Xiamen, China
2. Xiamen Key Laboratory of Computer Vision and Pattern Recognition and Fujian Key Laboratory of Big Data Intelligence and Security, Huaqiao University, Xiamen, China
3. Department of Computer Science and Institute of Research and Continuing Education, Hong Kong Baptist University, Hong Kong, China
4. Center for Future Multimedia and School of Computer Science and Engineering, University of Electronic Science and Technology of China, Chengdu, China
5. State Key Laboratory of Integrated Services Networks, Xidian University, Xi’an, China