Sang Aijun Hexin Chen Feng Hua Deng Linlin The Research for Color Image Encoding Based on 4-D n Order Orthogonal Matrix. 947-950 2008 CSSE (2) http://dx.doi.org/10.1109/CSSE.2008.1180 conf/csse/2008-2 db/conf/csse/csse2008-2.html#AijunHHL08