opencv获取图像边框

1.源码实现

#include <cstdio>
#include <iostream>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>

using namespace std;
using namespace cv;

void thresh_callback(Mat &src_gray, const int thresh)
{
    Mat canny_output;
    vector<vector<Point>> contours;
    vector<Vec4i> hierarchy;
    RNG rng(12345);

    //用Canny算子检测边缘
    Canny(src_gray, canny_output, thresh, 255, 3);

    //寻找轮廓
    findContours(canny_output, contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE, Point(0, 0));

    //多边形逼近轮廓 + 获取矩形和圆形边界框
    vector<vector<Point>> contours_poly(contours.size());
    vector<Rect> boundRect(contours.size());
    vector<Point2f>center(contours.size());
    vector<float>radius(contours.size());

    for(int i = 0; i < contours.size(); i++)
    {
        approxPolyDP(Mat(contours[i]), contours_poly[i], 3, true);
        boundRect[i] = boundingRect(Mat(contours_poly[i]));
        minEnclosingCircle(contours_poly[i], center[i], radius[i]);
    }

    //画多边形轮廓 + 包围的矩形框 + 圆形框
    Mat drawing = Mat::zeros(canny_output.size(), CV_8UC3);
    for(int i = 0; i< contours.size(); i++)
    {
        Scalar color = Scalar(rng.uniform(0, 255), rng.uniform(0,255), rng.uniform(0,255));

        //drawContours(drawing, contours_poly, i, color, 1, 8, vector<Vec4i>(), 0, Point());
        //rectangle(drawing, boundRect[i].tl(), boundRect[i].br(), color, 2, 8, 0);
        circle(src_gray, center[i], (int)radius[i], color, 2, 8, 0);
    }

    //保存结果
    imwrite("Contours.jpg", src_gray);
}

int main()
{
    //加载源图像
    Mat src = imread("10.jpg", 1);
    Mat src_gray;

    //转成灰度并模糊化降噪
    cvtColor(src, src_gray, CV_BGR2GRAY);
    blur(src_gray, src_gray, Size(3,3));

    thresh_callback(src_gray, 65);

    return 0;
}

2.编译源码

$ g++ -o test test.cpp -std=c++11 -I/usr/local/include/opencv4 -L/usr/local/lib -lopencv_core -lopencv_highgui -lopencv_imgproc -lopencv_ml -Wl,-rpath=/usr/local/lib

3.运行及其结果

10.jpg
Contours.jpg