クロスの描画
write_cross.cpp
#include <opencv2/opencv.hpp>
using namespace cv;
int main(int argc, const char * argv[])
{
//Mat img = imread( "image.jpg" );
//単色画像の生成(参考:http://opencv.jp/cookbook/opencv_mat.html の 「cv::vecを使う」
cv::Mat_<cv::Vec3b> img(300, 300, cv::Vec3b(0,200,0)); // 追加
imshow("1", img );
//参考: https://docs.opencv.org/3.4/d6/d6e/group__imgproc__draw.html
//cv::drawMarker (Mat &img, Point position, const Scalar &color, int markerType=MARKER_CROSS, int markerSize=20, int thickness=1, int line_type=8)
cv::drawMarker(img, cv::Point(100,100), cv::Vec3b(0,0,200), cv::MARKER_CROSS);
imshow("2", img );
imwrite("img.png",img);
waitKey(0);
return 0;
}