获取限制x值范围内轮廓的y值最小的点

	int srch=src->height;

	int leftx=minpointx*1.2;//minpointx为轮廓的最左侧的点的x值
	int rightx=maxpointx*0.8;//maxpointx为轮廓的最右侧的点的x值

	bool flag;
	int minvalue;

	vector<CvPoint> minpoint,maxpoint;

	for (i=leftx;i<rightx;i++)
	{
		minvalue=srch;
		flag=false;
		for (int j=0;j<contour1.size();j++)
		{
			CvPoint pt1=contour1[j];
			pointx=pt1.x;
			pointy=pt1.y;
			if (pointx==i)
			{
				flag=true;
				if (pointy<minvalue)
				{
					minvalue=pointy;
				}
			}
		}
		if (flag==true)
		{
			minpoint.push_back(cvPoint(i,minvalue));
		}
	}