Hu Junhong is a Ph.D. candidate in Institute of Pattern Recognition & Artificial Intelligence, Huazhong University of Science and Technology, Wuhan, China. Her research interests include pattern recognition, image processing, image fusion and parallel system. E-mail: jhhu@phy.cc Zhang Tianxu is currently a professor and director in Institute of Pattern Recognition and Artificial Intelligence, Huazhong University of Science and Technology, Wuhan, China. His research interests include image processing, computer vision, pattern recognition, and medical imaging.