一、最小外接圆
1 #include "opencv2/opencv.hpp"
2 #include<iostream>
3 using namespace std;
4 using namespace cv;
5
6 void main() {
7 Mat srcImg = imread("E://10.png");
8 imshow("src", srcImg);
9 Mat dstImg = srcImg.clone();
10 GaussianBlur(srcImg, srcImg, Size(3, 3), 0, 0);
11 cvtColor(srcImg, srcImg, CV_BGR2GRAY);
12 Canny(srcImg, srcImg, 100, 200);
13 imshow("Canny", srcImg);
14
15 //查找轮廓
16 vector<vector<Point>> contours;
17 vector<Vec4i> hierarcy;
18 findContours(srcImg, contours, hierarcy, CV_RETR_TREE, CV_CHAIN_APPROX_NONE);
19 cout << "num=" << contours.size() << endl;
20
21 Point2f center; //定义圆中心坐标
22 float radius; //定义圆半径
23 for (int i = 0; i<contours.size(); i++) //依次遍历每个轮廓
24 {
25 minEnclosingCircle(Mat(contours[i]), center, radius);
26 drawContours(dstImg, contours, i, Scalar(0, 0, 255), 2, 8);
27 circle(dstImg, center, radius, Scalar(0, 255, 0), 2, 8); //绘制第i个轮廓的最小外接圆
28 }
29 imshow("dst", dstImg);
30
31 waitKey(0);
32 }
二、椭圆拟合
1 #include "opencv2/opencv.hpp"
2 using namespace cv;
3
4 void main() {
5 Mat srcImg = imread("E://10.png");
6 imshow("src", srcImg);
7 Mat dstImg = srcImg.clone();
8 GaussianBlur(srcImg, srcImg, Size(3, 3), 0, 0);
9 cvtColor(srcImg, srcImg, CV_BGR2GRAY);
10 Canny(srcImg, srcImg, 100, 200);
11 imshow("Canny", srcImg);
12
13 //查找轮廓
14 vector<vector<Point>> contours;
15 vector<Vec4i> hierarcy;
16 findContours(srcImg, contours, hierarcy, CV_RETR_TREE, CV_CHAIN_APPROX_NONE);
17
18 vector<RotatedRect> box(contours.size());
19 Point2f rect[4];
20 for (int i = 0; i<contours.size(); i++)
21 {
22 box[i] = fitEllipse(Mat(contours[i]));
23 //ellipse(dstImg, box[i].center, Size(box[i].size.width/2, box[i].size.height/2), box[i].angle, 0, 360, Scalar(0, 255, 0), 2, 8);
24 ellipse(dstImg, box[i], Scalar(0, 255, 0), 2, 8);
25 }
26 imshow("dst", dstImg);
27
28 waitKey(0);
29 }
三、逼近多边形曲线
1 #include "opencv2/opencv.hpp"
2 using namespace cv;
3
4 void main() {
5 Mat srcImg = imread("E://02.jpg");
6 imshow("src", srcImg);
7 Mat dstImg = srcImg.clone();
8 Mat dstImg2(srcImg.size(), CV_8UC3, Scalar::all(0));//全黑图像
9
10 GaussianBlur(srcImg, srcImg, Size(3, 3), 0, 0);
11 cvtColor(srcImg, srcImg, CV_BGR2GRAY);
12 //Canny(srcImg, srcImg, 100, 200);
13 threshold(srcImg, srcImg, 200, 255, CV_THRESH_BINARY_INV);
14 imshow("threshold", srcImg);
15
16 vector<vector<Point>> contours;
17 vector<Vec4i> hierarcy;
18 findContours(srcImg, contours, hierarcy, CV_RETR_TREE, CV_CHAIN_APPROX_NONE);
19 vector<vector<Point>> contours_poly(contours.size());
20
21 for (int i = 0; i<contours.size(); i++)
22 {
23 approxPolyDP(Mat(contours[i]), contours_poly[i],15, true);//true曲线封闭，反之不封闭
24 drawContours(dstImg, contours, i, Scalar(0, 255, 0), 2, 8);//绘制轮廓
25 drawContours(dstImg2, contours_poly, i, Scalar(0, 255, 255), 2, 8); //绘制多边形逼近
26 }
27 imshow("dst", dstImg);
28 imshow("approx", dstImg2);
29
30 waitKey(0);
31 }
四、计算轮廓面积及长度（可用于轮廓筛选）
1 #include "opencv2/opencv.hpp"
2 #include<iostream>
3 using namespace std;
4 using namespace cv;
5
6 void main() {
7 Mat srcImg = imread("E://33.jpg");
8 imshow("src", srcImg);
9 Mat dstImg = srcImg.clone();
10 Mat dstImg2(srcImg.size(), CV_8UC3, Scalar::all(0));
11
12 GaussianBlur(srcImg, srcImg, Size(3, 3), 0, 0);
13 cvtColor(srcImg, srcImg, CV_BGR2GRAY);
14 //Canny(srcImg, srcImg, 100, 200);
15 threshold(srcImg, srcImg, 200, 255, CV_THRESH_BINARY);
16 imshow("threshold", srcImg);
17
18 vector<vector<Point>> contours;
19 vector<Vec4i> hierarcy;
20 findContours(srcImg, contours, hierarcy, CV_RETR_TREE, CV_CHAIN_APPROX_NONE);
21 cout << "num=" << contours.size() << endl;
22
23 for (int i = 0; i<contours.size(); i++)
24 {
25 double area = contourArea(contours[i]);//计算第i个轮廓的面积
26 cout<<"area--"<<i<<"---"<<area<<endl;
27
28 double length = arcLength(contours[i], true);
29 cout << "length--" << i << "---" << length << endl;
30 //if(area>10000) //面积大约1W
31 //if(area> 100 && area<300)
32
33 if (length<300 && area>300)
34 drawContours(dstImg, contours, i, Scalar(0, 0, 255), 2, 8);
35 }
36 imshow("dst", dstImg);
37 waitKey(0);
38 }
五、提取不规则轮廓
1 #include "opencv2/opencv.hpp"
2 using namespace cv;
3
4 void main() {
5 Mat srcImg = imread("E://220.jpg");
6 imshow("src", srcImg);
7 Mat dstImg = srcImg.clone(); //原图备份
8 Mat tempImg = srcImg.clone(); //原图备份
9 Mat tempImg2(srcImg.size(), CV_8UC3, Scalar::all(0)); //定义全黑的和原图一样大小的图像
10 Mat draw(srcImg.size(), CV_8UC3, Scalar::all(0));
11 Mat tempImg3(srcImg.size(), CV_8UC3, Scalar::all(0));
12
13 GaussianBlur(srcImg, srcImg, Size(3, 3), 0, 0);
14 cvtColor(srcImg, srcImg, CV_BGR2GRAY);
15 threshold(srcImg, srcImg, 100, 255, CV_THRESH_BINARY); //二值化
16 imshow("threshold", srcImg);
17
18 vector<vector<Point>> contours;
19 vector<Vec4i> hierarcy;
20 findContours(srcImg, contours, hierarcy, CV_RETR_TREE, CV_CHAIN_APPROX_NONE);
21 while (1)
22 {
23 for (int i = 0; i<contours.size(); i++)
24 {
25 tempImg2.copyTo(draw); //每次进入将draw清空为全黑
26 tempImg2.copyTo(tempImg3);
27 //drawContours(dstImg, contours, i, Scalar(0, 255, 0), 5, 8);
28 drawContours(draw, contours, i, Scalar(255, 255, 255), -1, 8);
29 Mat mask; //定义掩码
30 cvtColor(draw, mask, CV_BGR2GRAY);
31 tempImg.copyTo(tempImg3, mask); //将tempImg 复制到tempImg3(只有mask部分被复制)
32 imshow("draw", draw);
33 imshow("result", tempImg3);
34 char key = waitKey();
35 if (key == 27) //按下Esc键跳出for循环
36 break;
37 }
38 break;
39 }
40 }
