1. School of Information Science and Technology, ShanghaiTech University, 393 Middle Huaxia Road, Pudong, Shanghai 201210, China
2. Institute for Infocomm Research, Agency for Science, Technology and Research (A*STAR), 1 Fusionopolis Way, Singapore 138632, Singapore
3. School of Computing, National University of Singapore, Computing 1, 13 Computing Drive, Singapore 117417, Singapore
4. College of Agriculture and Life Sciences, Cornell University, 260 Roberts Hall, Ithaca, NY 14853, USA
5. School of Computer Science and Technology, Nanjing Tech University, 30 Puzhu Road, Nanjing 211816, China
6. Shanghai Engineering Research Center of Intelligent Vision and Imaging, 393 Middle Huaxia Road, Pudong, Shanghai 201210, China