Basic data persistence and storage

Before we finish this chapter, we will explore the OpenCV functions to store and read our data. In many applications, such as calibration or machine learning, when we are done with the calculations, we need to save the results in order to retrieve them in the next executions. For this purpose, OpenCV provides an XML/YAML persistence layer.

Writing to a file storage

To write a file with some OpenCV data or other numeric data, we can use the FileStorage class using the streaming c operator such as STL streaming:

#include "opencv2/opencv.hpp"
using namespace cv;

int main(int, char** argv)
{
    // create our writter
    FileStorage fs("test.yml", FileStorage::WRITE);
    // Save an int
    int fps= 5;
    fs << "fps" << fps;
    // Create some mat sample
    Mat m1= Mat::eye(2,3, CV_32F);
     Mat m2= Mat::ones(3,2, CV_32F);
     Mat result= (m1+1).mul(m1+3);
     // write the result
    fs << "Result" << result;
    // release the file...