1. Faculty of Information Engineering and Automation, Kunming University of Science and Technology , Kunming, Yunnan 650500, P. R. China and Computer Technology Application Key Lab of Yunnan Province, Kunming University of Science and Technology, Kunming, Yunnan 650500 , P. R. China
2. Faculty of Information Engineering and Automation, Kunming University of Science and Technology , Kunming, Yunnan 650500 , P. R. China
3. Guangxi Key Laboratory of Multimedia Communications and Network Technology, Guangxi University , Nanning 530004 , China