openCV2马拉松第19圈——Harris角点检测（自己实现）

#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 variables
Mat src, src_gray;
int thresh = 200;
int max_thresh = 255;

char* source_window = "Source image";
char* corners_window = "Corners detected";

/// Function header
void cornerHarris_demo( int, void* );

/** @function main */
int main( int argc, char** argv )
{
  /// Load source image and convert it to gray
  src = imread( argv[1], 1 );
  cvtColor( src, src_gray, CV_BGR2GRAY );

  /// Create a window and a trackbar
  namedWindow( source_window, CV_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 */
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, CV_WINDOW_AUTOSIZE );
  imshow( corners_window, dst_norm_scaled );
}

#include "opencv2/highgui/highgui.hpp"  
#include "opencv2/imgproc/imgproc.hpp"  
#include <cmath>
#include <iostream>
using namespace cv;   

Mat harris(Mat &im, double sigma, int thresh, int radius){
    Mat dx,dy,Ix,Iy,Ix2,Iy2,Ixy,cim;

    Sobel( im, Ix, CV_64F, 1, 0, 3);   //算法第一步，计算水平垂直差分
    Sobel( im, Iy, CV_64F, 0, 1, 3);

    int ksize = max(1, (int)(6*sigma));
    if(ksize % 2 == 0)
    	ksize++;
	GaussianBlur(Ix.mul(Ix), Ix2, Size(ksize, ksize), sigma);   //算法第二步，计算二阶高斯差分矩阵   
	GaussianBlur(Iy.mul(Iy), Iy2, Size(ksize, ksize), sigma);
	GaussianBlur(Ix.mul(Iy), Ixy, Size(ksize, ksize), sigma);

	//Harris corner measure
	//cim = (Ix2.*Iy2 - Ixy.^2)./(Ix2 + Iy2);
	cim = (Ix2.mul(Iy2) - Ixy.mul(Ixy)) / (Ix2+Iy2);            //算法第三步，计算响应函数，我使用了另外一种
	
    Mat structedElement(radius, radius, CV_8U, Scalar(1));
    Mat mx,norm_cim;
    normalize( cim, norm_cim, 0, 255, NORM_MINMAX, CV_8U, Mat() );
	dilate(norm_cim, mx, structedElement);
	norm_cim = ( norm_cim == mx) & (norm_cim>thresh);           //算法第4第5步融合，非极大值抑制和阀值检测	

	return norm_cim;
}

int main( int, char** argv )  
{  
	Mat src,gray;
	
    src = imread( argv[1] );
    cvtColor( src, gray, CV_RGB2GRAY );
    
	Mat corners = harris(gray, 1.5, 30, 2);
	for( int j = 0; j < corners.rows ; j++ ) { 
		for( int i = 0; i < corners.cols; i++ ) {
            if( corners.at<unsigned char>(j,i) > 0)
			{
				circle( gray, Point( i, j ), 3,  Scalar(0), 2, 8, 0 );
			}
		}
	}
    
    namedWindow("result", 1); 
    imshow("result", gray);
    waitKey();  
    return 0;  
}