6D Marr, E Hildreth. Theory of Edge Detection[A]. Proc of the Royal Society[C]. 1980, 187--207.
7B Jahne. Digital Image Processing (Fifth Edition)[M]. Heidelberg: Springer, 2002.
8C L Novak, S A Shafer. Color edge detection[A]. Proc of DARPA Image Understanding Workshop[C]. 1987. 35--37.
9J Fan, W G Aref, M Hacid, et al. An improved automatic isotropic color edge detection technique [ J ]. Pattern Recognition Letters, 2001, 22(3) : 1419--1429.
10S K Naik, C A Murthy. Standardization of edge magnitude in color images[J]. IEEE Transactions on Image Processing, 2006, 15 (9) : 2588--2595.