1. Guangxi Key Laboratory of Trusted Software, Guilin University of Electronic Technology, Guilin, China
2. Guangxi Colleges and Universities Key Laboratory of Intelligent Processing of Computer Images and Graphics, Guilin University of Electronic Technology, Guilin, China
3. School of Computer and Software, Nanjing University of Information Science & Technology, Nanjing, China
4. Department of Information Engineering and Computer Science, Feng Chia University, Taichung, Taiwan