Yvan G. Leclerc Steven W. Zucker The Local Structure of Image Discontinuities in One Dimension. 341-355 1987 9 IEEE Trans. Pattern Anal. Mach. Intell. 3 http://dx.doi.org/10.1109/TPAMI.1987.4767918 db/journals/pami/pami9.html#LeclercZ87