C++ OpenCv二值化找圓心座標

金灿灿發表於2024-11-05
C++OpenCV

思路：影像轉為灰度圖，然後二值化得到只有0或255的點座標，此處圓是黑點，所以新增所有畫素值為0的座標。在這些座標中找到圓上最左邊、最頂端、最右邊、最底端的四個點，這時可求出圓心座標。

.cpp檔案



#include <opencv2/opencv.hpp>
#include <iostream>
#include <cstdlib>
#include <windows.h>
#include <map>
#include <any>



// 1.獲取圖片
cv::Mat src = cv::imread("D:\\1.bmp");

// 2.將彩色影像轉換為灰度影像
cv::Mat gray_image;
cv::cvtColor(src, gray_image, cv::COLOR_BGR2GRAY);

// 3.二值化處理
cv::Mat dst;
cv::threshold(gray_image, dst, threshold, 255, cv::THRESH_BINARY);

// 4.找到所有目標座標
cv::Point leftPoint;
cv::Point rightPoint;
cv::Point topPoint;
cv::Point bottomPoint;
std::vector<cv::Point> points;
for (int i = 0; i < dst.rows; ++i) {
    for (int j = 0; j < dst.cols; ++j) {
        if (dst.at<uchar>(i, j) != 255) { // 0:白色、255:黑色
            cv::Point tempPoint = cv::Point(j, i);
                        // 去除邊緣干擾點位，按實際需求新增
            if (j < 50 || i < 50) {
                continue;
            }
            // 賦值初始座標
            if (leftPoint.x == 0 && leftPoint.y == 0) {
                leftPoint = tempPoint;
            }
            if (rightPoint.x == 0 && rightPoint.y == 0) {
                rightPoint = tempPoint;
            }
            if (topPoint.x == 0 && topPoint.y == 0) {
                topPoint = tempPoint;
            }
            if (bottomPoint.x == 0 && bottomPoint.y == 0) {
                bottomPoint = tempPoint;
            }

            points.push_back(tempPoint); // 注意OpenCV的座標系是(列,行)

            //else {
            if (leftPoint.x == 0 || tempPoint.x < leftPoint.x) {
                leftPoint = tempPoint;
            }
            if (topPoint.y == 0 || tempPoint.y < topPoint.y) {
                topPoint = tempPoint;
            }
            if (rightPoint.x == 0 || tempPoint.x > rightPoint.x) {
                rightPoint = tempPoint;
            }
            if (bottomPoint.y == 0 || tempPoint.y > bottomPoint.y) {
                bottomPoint = tempPoint;
            }
            //}
        }
    }
}

// 5.求圓半徑，
int r1 = rightPoint.x - leftPoint.x;
int r2 = bottomPoint.y - topPoint.y;
int r = (r1 + r2) / 2;



// 6.求圓心座標
cv::Point circleCenter(leftPoint.x + r, topPoint.y + r);


// 7.對圓畫框
// 7.1.定義矩形的左上角和右下角座標
cv::Point2f rect_start(leftPoint.x, topPoint.y);
cv::Point2f rect_end(rightPoint.x, bottomPoint.y);


// 7.2.畫矩形框
cv::rectangle(src, rect_start, rect_end, cv::Scalar(0, 255, 0));




 






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