Binary Image Thinning Algorithms // Thinning (skeletonization) algorithms for binary raster images. Provides seven algorithms behind a single dispatching function: Zhang-Suen (Zhang and Suen 1984) doi:10.1145/357994.358023, Guo-Hall (Guo and Hall 1989) doi:10.1145/62065.62074, a 2-D adaptation of Lee (Lee, Kashyap, and Chu 1994) doi:10.1006/cgip.1994.1042, K3M (Saeed, Tabedzki, Rybnik, and Adamski 2010) doi:10.2478/v10006-010-0024-4, the parallel form commonly attributed to Hilditch (1969, in 'Machine Intelligence 4'), OPTA / SPTA (Naccache and Shinghal 1984), and Holt and colleagues (1987) doi:10.1145/12527.12531. Also provides the medial axis transform (Blum 1967) and a distance transform implementation following Felzenszwalb and Huttenlocher (2012) doi:10.4086/toc.2012.v008a019. The thin() API selects the algorithm by name, defaulting to Zhang-Suen. Complements the morphology in the 'EBImage' package, which does not provide a thinning operator.