g++ main.cpp -std=c++11 -o out `pkg-config opencv --cflags --libs`

drawRandomImage

#include <opencv2/opencv.hpp>
#include <random>

using namespace std;
using namespace cv;

int rand_(int range){
	std::random_device rnd;     // 非決定的な乱数生成器
	return rnd()%range;
}

int main(void){
	for(int cnt=0;cnt<1000;cnt++){
		Mat image = Mat::zeros(500,500,CV_8UC3);
		std::string fname = "rectangle_middle1/7_" + std::to_string(cnt) + ".jpg";
		for(int el=0;el<1;el++){
			Point pt1(100,100);
			Point pt2(400,400);
			// Point pt1(rand_(250),rand_(250));
			// Point pt2(250+rand_(250),250+rand_(250));
			rectangle(image,pt1,pt2,Scalar(rand_(200), rand_(200), rand_(200)),
					3,8,0);
			// Point center(250,250);
			// ellipse(image, center, Size(rand_(200), rand_(200)), 0, 0, 360,
			// 		Scalar(rand_(200), rand_(200), rand_(200)), -1, 8, 0);
		}
		imwrite(fname,image);
	}
	return 0;
}