寻找包裹轮廓的最小正矩形：boundingRect 函数
结果矩阵应满足：① 轮廓上的点均在矩阵空间内。② 矩阵是正矩阵（矩形的边界与图像边界平行）。
Rect boundingRect(InputArray points);
代码示例：
#include<opencv.hpp>
#include<iostream>
using namespace cv;
using namespace std;
int main(){
Mat src = imread("C:/Users/齐明洋/Desktop/7.jpg");
imshow("src", src);
Mat gray, bin_img;
cvtColor(src, gray, COLOR_BGR2GRAY); //将原图转换为灰度图
imshow("gray", gray);
//二值化
threshold(gray, bin_img, 150, 255, THRESH_BINARY_INV);
imshow("bin_img", bin_img);
//寻找最外围轮廓
vector<vector<Point> >contours;
findContours(bin_img, contours, RETR_EXTERNAL, CHAIN_APPROX_NONE);
//绘制边界矩阵
RNG rngs = { 12345 };
Mat dst = Mat::zeros(src.size(), src.type());
for (int i = 0; i < contours.size(); i++) {
Scalar colors = Scalar(rngs.uniform(0, 255), rngs.uniform(0, 255), rngs.uniform(0, 255));
drawContours(dst, contours, i, colors, 1);
Rect rects = boundingRect(contours[i]);
rectangle(dst, rects, colors, 2);
}
imshow("dst", dst);
waitKey(0);
}
效果演示：
寻找包裹轮廓的最小斜矩形：minAreaRect 函数
结果矩阵应满足：① 轮廓上的点均在矩阵空间内。② 没有面积更小的满足条件的矩阵（与 boundingRect 返回结果的区别是：矩形的边界不必与图像边界平行）。
RotatedRect minAreaRect(InputArray points);
代码示例：
#include<opencv.hpp>
#include<iostream>
#include<vector>
using namespace cv;
using namespace std;
int main() {
Mat src = imread("C:/Users/齐明洋/Desktop/7.jpg");
imshow("src", src);
Mat gray, bin_img;
cvtColor(src, gray, COLOR_BGR2GRAY); //将原图转换为灰度图
imshow("gray", gray);
//二值化
threshold(gray, bin_img, 150, 255, THRESH_BINARY_INV);
imshow("bin_img", bin_img);
//寻找最外围轮廓
vector<vector<Point> >contours;
findContours(bin_img, contours, RETR_EXTERNAL, CHAIN_APPROX_NONE);
//绘制最小边界矩阵
RNG rngs = { 12345 };
Mat dst = Mat::zeros(src.size(), src.type());
Point2f pts[4];
for (int i = 0; i < contours.size(); i++) {
Scalar colors = Scalar(rngs.uniform(0, 255), rngs.uniform(0, 255), rngs.uniform(0, 255));
drawContours(dst, contours, i, colors, 1);
RotatedRect rects = minAreaRect(contours[i]);
rects.points(pts);
for (int i = 0; i < 4; i++) {
line(dst, pts[i], pts[(i + 1) % 4], colors, 2);
}
}
imshow("dst", dst);
waitKey(0);
}
效果演示：
借鉴博客：https://www.cnblogs.com/little-monkey/p/7429579.html
http://www.pianshen.com/article/4286104294/
opencv —— boundingRect、minAreaRect 寻找包裹轮廓的最小正矩形、最小斜矩阵
原文：https://www.cnblogs.com/bjxqmy/p/12347355.html