Added cornerSubPix_Demo.cpp tutorial sample code

samples/cpp/tutorial_code/TrackingMotion/cornerSubPix_Demo.cpp

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+/**
+ * @function cornerSubPix_Demo.cpp
+ * @brief Demo code for refining corner locations
+ * @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 variables
+Mat src, src_gray;
+
+int maxCorners = 10;
+int maxTrackbar = 25;
+
+RNG rng(12345);
+char* source_window = "Image";
+
+/// Function header
+void goodFeaturesToTrack_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 Window
+  namedWindow( source_window, CV_WINDOW_AUTOSIZE );
+
+  /// Create Trackbar to set the number of corners
+  createTrackbar( "Max  corners:", source_window, &maxCorners, maxTrackbar, goodFeaturesToTrack_Demo );  
+
+  imshow( source_window, src );
+
+  goodFeaturesToTrack_Demo( 0, 0 );
+
+  waitKey(0);
+  return(0);
+}
+
+/**
+ * @function goodFeaturesToTrack_Demo.cpp
+ * @brief Apply Shi-Tomasi corner detector
+ */
+void goodFeaturesToTrack_Demo( int, void* )
+{
+  if( maxCorners < 1 ) { maxCorners = 1; }
+  
+  /// Parameters for Shi-Tomasi algorithm
+  vector<Point2f> corners;
+  double qualityLevel = 0.01;
+  double minDistance = 10;
+  int blockSize = 3;
+  bool useHarrisDetector = false;
+  double k = 0.04;
+
+  /// Copy the source image
+  Mat copy;
+  copy = src.clone();
+
+  /// Apply corner detection
+  goodFeaturesToTrack( src_gray, 
+		       corners,
+		       maxCorners,
+		       qualityLevel,
+		       minDistance,
+		       Mat(),
+		       blockSize,
+		       useHarrisDetector,
+		       k );
+  
+
+  /// Draw corners detected
+  cout<<"** Number of corners detected: "<<corners.size()<<endl;
+  int r = 4;
+  for( int i = 0; i < corners.size(); i++ )
+     { circle( copy, corners[i], r, Scalar(rng.uniform(0,255), rng.uniform(0,255), rng.uniform(0,255)), -1, 8, 0 ); }
+
+  /// Show what you got
+  namedWindow( source_window, CV_WINDOW_AUTOSIZE );
+  imshow( source_window, copy );  
+
+  /// Set the neeed parameters to find the refined corners
+  Size winSize = Size( 5, 5 );
+  Size zeroZone = Size( -1, -1 );
+  TermCriteria criteria = TermCriteria( CV_TERMCRIT_EPS + CV_TERMCRIT_ITER, 40, 0.001 );
+
+  /// Calculate the refined corner locations
+  cornerSubPix( src_gray, corners, winSize, zeroZone, criteria );
+
+  /// Write them down
+  for( int i = 0; i < corners.size(); i++ )
+     { cout<<" -- Refined Corner ["<<i<<"]  ("<<corners[i].x<<","<<corners[i].y<<")"<<endl; }	
+}
+