1. College of Computer Science and Technology, Chongqing University of Posts and Telecommunications, Chongqing 400065, P. R. China
2. Chongqing Key Laboratory of Image Cognition, Chongqing University of Posts and Telecommunications, Chongqing 400065, P. R. China
3. Hubei Key Laboratory of Intelligent, Vision Based Monitoring for Hydroelectric Engineering, China Three Gorges University, Yichang 443002, P. R. China
4. China Yichang Key Laboratory of Intelligent, Vision Based Monitoring for Hydroelectric Engineering, China Three Gorges University, Yichang 443002, P. R. China