A question of reading yaml file

edit

cv::FileStorage is a "key-value" store, to save different objects, you need unique keys, "name" isn't unique.

so, you either do, what @sturkmen proposes, give any item a unique name, or wrap it into "objects", like this:

Mat m1(10,10,CV_8UC3); m1=17;
Mat m2(6,8,CV_32F); m2=3;

FileStorage fs("my.yml", FileStorage::WRITE);

fs << "object1" << "{"; // an object with a unique name.
fs << "Date of storage" << "Wed Jul 26 16:45:46 2017\n";
fs << "Mat" << m1; // the "internal" keys can be as generic as you want
fs << "}";

fs << "object2" << "{";
fs << "Date of storage" << "Wed Jul 26 16:48:16 2017\n";
fs << "Mat" << m2;
fs << "}";

fs.release();

fs.open("my.yml", FileStorage::READ);
FileNode fn = fs["object2"];  // retrieve the object node
Mat M2;  String date;
fn["Mat"] >> M2;      // and its data
fn["Date of storage"] >> date;
cerr << date << endl;
cerr << M2 << endl;

check the code below

#include "opencv2/imgproc.hpp"
#include "opencv2/highgui.hpp"

#include <iostream>

using namespace cv;
using namespace std;


bool saveMats(const Mat m1, const Mat m2, String file_path)
{
    FileStorage fs(file_path, FileStorage::WRITE);

    fs << "name" << "object1";
    fs << "object1" << m1;
    fs << "object2" << m2;

    return true;
}


int main()
{

    Mat m1(5, 5, CV_8UC1, Scalar(127));
    Mat m2(6, 6, CV_8UC1, Scalar(128));
    saveMats(m1, m2, "test.yml");

    FileStorage fs("test.yml", FileStorage::READ);
    FileNode fn = fs.root();

    Mat r1,r2;
    cv::read(fn["object1"], r1);
    cv::read(fn["object2"], r2);
    cout << r1 << endl;
    cout << r2;
    imshow("just for waiting", r1);
    waitKey();

    return 0;
}