3 ways to iterate through the matrix and comparison - OpenCV 행렬 원소를 모두 참조하는 세 가지 방법

There are 3 ways to iterate through the matrix. Below code shows how to use them and compares their speed.

행렬 원소를 모두 참조하는 세 가지 방법을 보여주고 속도를 비교 합니다.

#include <opencv2/opencv.hpp>
 
using namespace std;
using namespace cv;
 
int main(int argc, char** argv)
{
    TickMeter tm;
    Mat mat = Mat::zeros(600, 800, CV_8UC1);
 
    tm.start();
    for (int i = 0; i < mat.rows; i++)
        for (int j = 0; j < mat.cols; j++)
            mat.at<uchar>(i, j)++;
    tm.stop();
    cout << ".at<> execution time: " << tm.getTimeSec() << endl;
    tm.reset();    
 
    tm.start();
    for (int i = 0; i < mat.rows; i++)
    {
        uchar* p = mat.ptr<uchar>(i);
        for (int j = 0; j < mat.cols; j++)
            p[j]++;
    }
    tm.stop();
    cout << ".ptr<> execution time: " << tm.getTimeSec() << endl;
    tm.reset();
 
    tm.start();
    for (MatIterator_<uchar> it = mat.begin<uchar>(); it != mat.end<uchar>(); it++)
        (*it)++;
    tm.stop();
    cout << "MatIterator execution time: " << tm.getTimeSec() << endl;
    tm.reset();
 
    return 0;
}