OpenCV案例(二)：选取圆对象
OpenCV提供了一些基本的形态学处理方法与绘图操作，比如膨胀、腐蚀、开闭操作、画圆，画椭圆，画线，画矩形，在图像里插入文字等功能。
代码：
-
#include <iostream> -
#include <opencv2/core/core.hpp> -
#include <opencv2/highgui/highgui.hpp> -
#include <opencv2/imgproc/imgproc.hpp> -
#include <opencv2/opencv.hpp> -
#include <math.h> -
#include <iostream> -
using namespace std; -
using namespace cv; -
//double threshold = 200.0; -
Mat BinaryImg,morhImage; -
int main() -
{ -
Mat img = imread("../img/33.png", IMREAD_GRAYSCALE); -
imshow("原图", img); -
threshold(img , BinaryImg ,0 ,255,THRESH_BINARY |THRESH_OTSU); -
imshow("二值化",BinaryImg); -
//形态学处理 -
Mat kernel = getStructuringElement(MORPH_RECT, Size(4, 4)); -
morphologyEx(BinaryImg, morhImage, MORPH_OPEN, kernel); //去掉杂点 -
imshow("形态学结果", morhImage); -
vector<vector<Point>> contours; -
Mat resutimg = Mat::zeros(img.size(),CV_8UC3); -
findContours(morhImage, contours, RETR_TREE, CHAIN_APPROX_SIMPLE); //找到图像轮廓 -
for (int i = 0; i < contours.size(); i++) -
{ -
double area = contourArea(contours[i]); //去掉小区域 -
if(area < 100 ) continue; -
Rect rect = boundingRect(contours[i]); //根据外轮廓长宽比率寻找圆 -
float ratio = (float)(rect.width) / rect.height; -
if (ratio > 0.9 && ratio < 1.1) -
{ -
drawContours(resutimg, contours, i, Scalar(0, 0, 250),-1); //找到圆的轮廓,-1代表填充 -
int x = rect.x + rect.width / 2; -
int y = rect.y + rect.height / 2; -
//circle(resutimg, Point(x, y), 2, Scalar(0, 0, 250),2); //画小圆点 -
cout << "circle area : " << area << endl; -
cout << "circle length : " << arcLength(contours[i], true); -
cout << "circle center : x= " << x<<" , y = "<< y << endl; -
} -
} -
imshow("result", resutimg); //绘制圆的轮廓与圆心 -
waitKey(0); -
}
结果：