opencv中連通區域分析

opencv版本：1.0

部分函數介紹：

1.cvFindContours -提取輪廓，函數原型如下：

/* Retrieves outer and optionally inner boundaries of white (non-zero) connected
   components in the black (zero) background */
CVAPI(int)  cvFindContours( CvArr* image, CvMemStorage* storage, CvSeq** first_contour,
                            int header_size CV_DEFAULT(sizeof(CvContour)),
                            int mode CV_DEFAULT(CV_RETR_LIST),
                            int method CV_DEFAULT(CV_CHAIN_APPROX_SIMPLE),
                            CvPoint offset CV_DEFAULT(cvPoint(0,0)));
           

2.cvContourArea-計算輪廓面積，函數原型如下：

/* Calculates area of a contour or contour segment */
CVAPI(double)  cvContourArea( const CvArr* contour,
                              CvSlice slice CV_DEFAULT(CV_WHOLE_SEQ),
                              int oriented CV_DEFAULT(0));
           

3.cvBoundingRect-計算包含輪廓的最小矩形，函數原型如下：

/* Calculates contour boundning rectangle (update=1) or
   just retrieves pre-calculated rectangle (update=0) */
CVAPI(CvRect)  cvBoundingRect( CvArr* points, int update CV_DEFAULT(0) );
           

4.cvDrawContours-函數原型如下：

/* Draws contour outlines or filled interiors on the image */
CVAPI(void)  cvDrawContours( CvArr *img, CvSeq* contour,
                             CvScalar external_color, CvScalar hole_color,
                             int max_level, int thickness CV_DEFAULT(1),
                             int line_type CV_DEFAULT(8),
                             CvPoint offset CV_DEFAULT(cvPoint(0,0)));
           

下面舉個例子說明：

#include <stdio.h>
#include <cv.h>
#include <highgui.h>


int main( int argc, char** argv )  
{
	IplImage* src = cvLoadImage("../win.png", CV_LOAD_IMAGE_GRAYSCALE);
	IplImage* dst = cvCreateImage(cvGetSize(src), 8, 3);
	CvMemStorage* storage = cvCreateMemStorage(0);

	cvNamedWindow("源圖像", 1);
	cvShowImage("源圖像", src);

	CvSeq* contour = 0;
	// 二值化(0/255)
	cvThreshold(src, src,120, 255, CV_THRESH_BINARY);	
	cvNamedWindow("二值圖", 1);
	cvShowImage("二值圖", src);

	// 提取輪廓
	int contour_num = cvFindContours(src, storage, &contour, sizeof(CvContour), CV_RETR_CCOMP, CV_CHAIN_APPROX_SIMPLE);
	cvZero(dst);		// 清空數組
	CvSeq *_contour = contour; 
	double maxarea = 0;
	double minarea = 100;
	int m = 0;

	//周遊輪廓（）
	for( ; contour != 0; contour = contour->h_next )  
	{  

		double tmparea = fabs(cvContourArea(contour));
		//删除面積小于100的輪廓
		if(tmparea < minarea)   
		{  
			cvSeqRemove(contour, 0); // 删除面積小于設定值的輪廓
			continue;
		}  

		//包含輪廓區域的最小矩形框
		CvRect aRect = cvBoundingRect( contour, 0 ); 

		//删除寬大于長的輪廓
		if ((aRect.width/aRect.height)<1)  
		{  
			cvSeqRemove(contour, 0); //删除寬高比例小于設定值的輪廓
			continue;
		}  

		//尋找面積最大的輪廓
		if(tmparea > maxarea)  
		{  
			maxarea = tmparea;
		}  
		m++;

		// 建立一個色彩值
		CvScalar color = CV_RGB( 0, 0, 255 );

		//max_level 繪制輪廓的最大等級。
		//如果等級為0，繪制單獨的輪廓。
		//如果為1，繪制輪廓及在其後的相同的級别下輪廓
		//如果值為2，所有的輪廓。如果等級為2，繪制所有同級輪廓及所有低一級輪廓，諸此種種
		//如果值為負數，函數不繪制同級輪廓，但會升序繪制直到級别為abs(max_level)-1的子輪廓

		/* Draws contour outlines or filled interiors on the image */
		/*CVAPI(void)  cvDrawContours( CvArr *img, CvSeq* contour,
									 CvScalar external_color, CvScalar hole_color,
									 int max_level, int thickness CV_DEFAULT(1),
									 int line_type CV_DEFAULT(8),
									 CvPoint offset CV_DEFAULT(cvPoint(0,0)));*/
        //1.img=dst 2.contour=contour 3.external_color=color 4.hole_color=color 5.max_level=-1
		int max_level = 0;
		cvDrawContours(dst, contour, color, color, max_level, 1, 8);	//繪制外部和内部的輪廓
	}   //輪廓周遊結束

	//重新指派
	contour = _contour;
	int count = 0;
	
	//周遊輪廓，繪制面積最大的輪廓
	for(; contour != 0; contour = contour->h_next)
	{  
		count++;
		double tmparea = fabs(cvContourArea(contour));
		//繪制面積最大的輪廓
		if (tmparea == maxarea)  
		{  
			CvScalar color = CV_RGB( 255, 0, 0); //紅色
			cvDrawContours(dst, contour, color, color, -1, 1, 8);
		}  
	}  

	printf("The total number of contours is:%d", count);

	cvNamedWindow("Components", 1);
	cvShowImage("Components", dst);
	cvWaitKey(0);

	cvDestroyWindow("二值圖");
	cvReleaseImage(&src);
	cvDestroyWindow("Components");
	cvReleaseImage(&dst);

	return 0;
}