Further considerations of a 1-subcycle parallel thinning algorithm

[[abstract]]© 1992 中國工程師學會-In this paper, the authors present two improved versions of a pseudo 1-subcycle parallel thinning algorithm which they proposed earlier (see Pattern Recognit., vol.22. no.3, p.267-82, 1989) and describe a two-stage structure to realize the 1-subcycle parallel algorithm. The purpose of the first improved algorithm is to produce the P8ET (perfect 8-curve excluding T-junction)-type thin line which is well-defined in general. This algorithm involves local branches containing T-junctions or quasi T-junctions. The second improved algorithm obtains an isotropic skeleton of an L-shape pattern, such that the visual quality of a skeleton is more satisfactory. In this algorithm, another set of thinning conditions especially designed is also involved. A two-stage structure, which consists of a thinning table and a control unit, is also described. The thinning table is used to provide the attributes of an input 3×3 local pattern. The control unit is used to check the removal of the center `1' pixel of this local pattern. The inputs of the control unit also comprise the outputs of other neighboring thinning tables. This structure can exactly implement the original 1-subcycle parallel algorithm[[department]]電機工程學