OpenCV找出图片中的圆并标注圆心

一、概述

  案例:输入一张图片找到图片中的一个圆,并标注圆心

  实现步骤:

    1.输入原图

    2.图像图像灰度化

    3.图像二值化

    4.执行形态学操作去除噪点

    5.边缘检测

    6.轮廓发现

    7.根据面积和纵横比过滤目标轮廓

    8.找出圆心并绘制圆心

    9.在原图上也绘制圆心并输出

二、代码示例

 //【1】载入图像
    Mat src = imread(filePath);
    Mat src_clone = src.clone();
    if(src.empty()){
        qDebug()<<"图片为空";
        return;
    }
    imshow("src",src);
    //21】转灰度图
    Mat gray;
    cvtColor(src,gray,COLOR_BGR2GRAY);
    //【3】图像二值化
    threshold(gray,gray,0,255,THRESH_BINARY|THRESH_OTSU);
    imshow("threshold",gray);
    //【4】执行形态学开操作去除噪点
    Mat kernel = getStructuringElement(MORPH_RECT,Size(20,20),Point(-1,-1));
    morphologyEx(gray,gray,MORPH_OPEN,kernel,Point(-1,-1),1);
    imshow("morphologyEx",gray);

    //【5】边缘检测
    Canny(gray,gray,0,255);
    imshow("canny",gray);

    //【6】轮廓发现
    vector<vector<Point>> contours;
    vector<Vec4i> her;
    findContours(gray,contours,her,RETR_TREE,CHAIN_APPROX_SIMPLE);
    Mat resultImage = Mat::zeros(gray.size(),CV_8UC3);
    RNG rng(12345);
    double area = 0.0;
    Point pRadius;
    for(size_t i = 0;i<contours.size();i++){
        double area = contourArea(contours[i],false);
         //【7】根据面积及纵横比过滤轮廓
        if(area>200){
            Rect rect = boundingRect(contours[i]);
            float scale = float(rect.width)/float(rect.height);
            if(scale<1.1&&scale>0.9){
                drawContours(resultImage,contours,i,Scalar(rng.uniform(0,255),rng.uniform(0,255),rng.uniform(0,255)),-1);
                int x = rect.width/2;
                int y = rect.height/2;
                 //【8】找出圆心并绘制
                pRadius=Point(rect.x+x,rect.y+y);
                circle(resultImage,pRadius,2,Scalar(0,0,255),2);
            }
        }

    }
     imshow("resultImage",resultImage);
    //【9】在原图上绘制圆心,这一步要不要都行,因为坐标都找出来了,可以随便标注
    circle(src_clone,pRadius,2,Scalar(0,0,255),2);
    imshow("src_clone",src_clone);

 

三、图片示例

 

posted on 2022-03-17 15:32  飘杨......  阅读(2884)  评论(0编辑  收藏  举报