Mark D. Wheeler Katsushi Ikeuchi Iterative Smoothed Residuals: A Low-Pass Filter for Smoothing With Controlled Shrinkage. 334-337 1996 18 IEEE Trans. Pattern Anal. Mach. Intell. 3 http://doi.ieeecomputersociety.org/10.1109/34.485562 db/journals/pami/pami18.html#WheelerI96