A CHINESE CHARACTER FILTER FOR MAP

Characters are special objects in scanned maps and engineering drawings. They will make the lines twist after thinning if having not been separated from lines. So it is useful to design an operator called “Chinese character filter”. It is a typical algorithm of pattern recognition, based on the three features: concentrated strokes, shape and size, and isolation. Expansion and erosion algorithm is first used to strengthen those features, and other algorithms like sliding frame algorithm are used to find the locations of characters based on the characteristic features. Then, it is easy to delete them with the known size and shape.