[1] School of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha 410004, China
[2] College of Science, South China Agricultural University, Guangzhou 510642, China
[3] School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275, China
[4] Department of Image System Science and Engineering, Pukyong National University, Pusan 608-739, Korea, Republic of