A geometric approach to stroke extraction for the Chinese calligraphy robot

Known as “the art of strokes”, Chinese calligraphy expresses its aesthetic through the strokes. A calligraphy learner practise the strokes and compose a calligraphic character by the strokes thereafter. Following the same process, the calligraphy robot, Callibot [2] needs to extract the strokes from a character. Therefore, we propose an approach to extract strokes using the geometric properties on the contour(s) of a character. A key discovery is that if two strokes intersect, the contour is concave; otherwise it is convex. The curvature vector defined in [1] is used to locate the vertexes whose interior angles are greater than 180° (these vertexes are named as C-points). C-points separate the contours into sub-contours. The corresponding sub-contours then form the basic strokes (i.e. dot stroke, horizontal stroke, vertical stroke, left-falling stroke and right-falling stroke). The experimental results show that this approach is feasible of extracting strokes from characters. This research is also useful for Chinese character recognition and calligraphic styles classification.