Critical points on a perfectly 8- or 6-connected thin binary line

摘要

A set of “logical pixel logic” based procedures is described and illustrated for detecting the near-minimal number of pixels on a perfectly 8- or 6-connected binary thin line which have to be retained to adequately approximate the original pixel string with a connected sequence of straight-line segments. The found critical points or pixels on the line are for practical purposes the same as those chosen by a person, were he asked to perform the same task. The method is fast and in practically all cases the approximating connected sequence of straight-line segments does not deviate by more than one pixel distance from the original pixel string. Experiments on Chinese characters have given very good results. The method could also be used as a preprocessing step to conventional iterative methods based on minimizing a distance criterion between the approximating straight-line segments and the pixels on the original binary line. It will be very useful in any field in which computational speed is one of the major concerns, such as industrial vision systems.