Basic data persistence and storage

Before finishing 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 finish performing a number of calculations, we need to save these results to retrieve them in subsequent operations. OpenCV provides an XML/YAML persistence layer to this end.

Writing to FileStorage

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

#include "opencv2/opencv.hpp" 
using namespace cv; 
 
int main(int, char** argv) 
{ 
   // create our writer 
    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...