The method can directly extract arc.The binary image is encoded with black horizontal runlength.A stripe region consists of correlative runlengths with the same width and topology.

• 对二值图象作水平黑游程编码，相关游程基于线宽与拓扑的一致性构成条形域，对其中多义域进行分裂得单义域（线段域和圆弧域）。