1. Department of Computer Science, Xiamen University, Xiamen 361005, Fujian, China
2. Key Lab of Intelligent Computing and Signal Processing, School of Computer Science and Technology, Anhui University, Hefei 230039, Anhui, China
3. Key Laboratory of Image Information Processing and Intelligent Control, School of Automation, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China