说明：  本例使用了opencv中图像数据结构IplImage ：首先进行第一次扫描，标记连通区域；然后对等价标记进行合并，最后进行第二次扫描，对等价标记进行重新标记。
(This example uses a data structure of the opencv: IplImage. First, scan for the first time, marking connected region then mark the merger of the equivalence, and finally a second scan, the equivalent re-mark will be finished.)