Kwangyoen Wohn Jian Wu Roger W. Brockett A Contour-Based Recovery of Image Flow: Iterative Transformation Method. 746-760 1991 13 IEEE Trans. Pattern Anal. Mach. Intell. 8 http://doi.ieeecomputersociety.org/10.1109/34.85666 db/journals/pami/pami13.html#WohnWB91