Non-recursive thinning algorithms using chain codes

Describes the development of contour generation thinning algorithms that are non-recursive. Two algorithms are presented, both of them involves the use of 4 sub-cycles. Additional data structures are incorporated in the chain code to ensure consistency in the propagation of contour pixels. In both algorithm, the 4-distance metric is used. The first algorithm erodes a 4-connected contour in an iteration. The second algorithm remembers the state of the bitmap at the beginning of an iteration, with the result that an 8-contour is eroded