霍夫变换(Hough Circle Transform)-圆检测

我就是我 2022-03-28 07:07 322阅读 0赞

[官网教程][Link 1]

**参数不太好选，API比较难用**

--------------------

## 代码 ##

#include <opencv2/opencv.hpp>
    #include <iostream>
    
    using namespace cv;
    using namespace std;
    
    //测试使用
    //int Max_Threshold = 300;
    //const int Max_Value = 600;
    
    //int Low_Threshold = 100;
    //const int Low_Value = 300;
    
    cv::Mat src_gray,src,Terminal;
    //测试使用
    //void MyCanny(int,void*)
    //{ 
    // Mat tmp;
    // cv::medianBlur(src_gray,tmp,5);
    // Canny(tmp,tmp,Low_Threshold,Max_Threshold,3);
    // imshow("Canny", tmp);
    // Terminal = tmp.clone(); 
    //}
    
    
    int main(void)
    { 
    
        src = imread("../res/coins.png");
    	if(src.empty())
    	{ 
    		cout << "can't load image" << endl;
    	}		
    	cvtColor(src,src_gray, cv::COLOR_BGR2GRAY);
    
        //测试使用
    	// createTrackbar("Canny High Threshold","Canny",&Max_Threshold,Max_Value,MyCanny);
    	// createTrackbar("Canny Low Threshold","Canny",&Low_Threshold,Low_Value,MyCanny);
    
    	cv::medianBlur(src_gray,src_gray,5);
    	Canny(src_gray,src_gray,180,600,3); //参数是自己通过createTrackbar调出来的
    	imshow("after Canny" , src_gray);
    
    	vector<Vec3f> circles;
    	HoughCircles(src_gray,circles, HOUGH_GRADIENT,1,100,200,20,50,200); //测试出来的参数，
    
    	for(int i=0; i<circles.size(); i++)
    	{ 
    		Vec3i c = circles[i];
    		Point center = Point(c[0],c[1]);
    
    		circle(src,center,1,Scalar(0,0,0),3,LINE_AA);
    		int radius = c[2];
    		circle(src,center,radius,Scalar(0,0,0),3,LINE_AA);
    	}
    
    	imshow("Hough Circles",src);
    		
    	waitKey(0);
    		
    	return 0;
    };

--------------------

结果：

先Canny进行边缘检测：

![20190109214658608.png][]

检测结果：

![20190109214800549.png][]

## OpenCV API ##

[void cv::HoughCircles][void cv_HoughCircles]  
(  
InputArray image,     // 8-bit, single-channel, grayscale input image.  
OutputArray circles,    // 输出检测到的圆，参数是 float型 (x,y,radius)  
int method,        // 检测方法： HOUGH\_GRADIENT  
double dp,        // accumulator resolution=(1/dp) × \\times ×image resolution  
double minDist,      //检测到两个圆之间的最小距离  
double param1 = 100,    // 内部调用了Canny edge ，这个是高阈值，低阈值是此参数的1/2  
double param2 = 100,    // 是霍夫空间检测圆心的收集器的阈值，  
int minRadius = 0,    // Minimum circle radius.  
int maxRadius = 0     //Maximum circle radius ，If < 0, 只检测圆心  
)

[Link 1]: https://docs.opencv.org/master/d4/d70/tutorial_hough_circle.html
[20190109214658608.png]: /images/20220328/91bc642e44bf4b3cb5cf7a739b0880d1.png
[20190109214800549.png]: /images/20220328/f1ae9551d8be4e25b918e24561eebd9d.png
[void cv_HoughCircles]: https://docs.opencv.org/master/dd/d1a/group__imgproc__feature.html#ga47849c3be0d0406ad3ca45db65a25d2d