Natasa Sladoje Joakim Lindblad High-Precision Boundary Length Estimation by Utilizing Gray-Level Information. 357-363 2009 31 IEEE Trans. Pattern Anal. Mach. Intell. 2 http://dx.doi.org/10.1109/TPAMI.2008.184 db/journals/pami/pami31.html#SladojeL09