Opencv-Harris corner detection

For the implementation routine of this article, see the English tutorial feature2d module.2d features framework-> Harris corner detector

The specific algorithm uses the Taylor expansion to obtain the maximum change point of the pixel value in the window, that is, the corner point position.

/** * @function cornerHarris_Demo.cpp * @brief Demo code for detecting corners using Harris-Stephens method * @author OpenCV team */#include "opencv2/highgui/highgui.hpp"#include "opencv2/imgproc/imgproc.hpp"#include <iostream>#include <stdio.h>#include <stdlib.h>using namespace cv;using namespace std;/// Global variablesMat src, src_gray;int thresh = 200;int max_thresh = 255;const char* source_window = "Source image";const char* corners_window = "Corners detected";/// Function headervoid cornerHarris_demo( int, void* );/** * @function main */int main( int, char** argv ){  /// Load source image and convert it to gray  src = imread( argv[1], 1 );  cvtColor( src, src_gray, COLOR_BGR2GRAY );  /// Create a window and a trackbar  namedWindow( source_window, WINDOW_AUTOSIZE );  createTrackbar( "Threshold: ", source_window, &thresh, max_thresh, cornerHarris_demo );  imshow( source_window, src );  cornerHarris_demo( 0, 0 );  waitKey(0);  return(0);}/** * @function cornerHarris_demo * @brief Executes the corner detection and draw a circle around the possible corners */void cornerHarris_demo( int, void* ){  Mat dst, dst_norm, dst_norm_scaled;  dst = Mat::zeros( src.size(), CV_32FC1 );  /// Detector parameters  int blockSize = 2;  int apertureSize = 3;  double k = 0.04;  /// Detecting corners  cornerHarris( src_gray, dst, blockSize, apertureSize, k, BORDER_DEFAULT );  /// Normalizing  normalize( dst, dst_norm, 0, 255, NORM_MINMAX, CV_32FC1, Mat() );  convertScaleAbs( dst_norm, dst_norm_scaled );  /// Drawing a circle around corners  for( int j = 0; j < dst_norm.rows ; j++ )     { for( int i = 0; i < dst_norm.cols; i++ )          {            if( (int) dst_norm.at<float>(j,i) > thresh )              {               circle( dst_norm_scaled, Point( i, j ), 5,  Scalar(0), 2, 8, 0 );              }          }     }  /// Showing the result  namedWindow( corners_window, WINDOW_AUTOSIZE );  imshow( corners_window, dst_norm_scaled );}