#include <stdio.h>

 #include <iostream>

 #include "opencv2/core/core.hpp"

 #include "opencv2/features2d/features2d.hpp"

 #include "opencv2/highgui/highgui.hpp"

 using namespace cv;

 void readme();

 /** @function main */

 int main( int argc, char** argv )

 {

   if( argc !=  )

    { return -; }

   Mat img_1 = imread( argv[], CV_LOAD_IMAGE_GRAYSCALE );

   Mat img_2 = imread( argv[], CV_LOAD_IMAGE_GRAYSCALE );

   if( !img_1.data || !img_2.data )

    { return -; }

   //-- Step 1: Detect the keypoints using SURF Detector

   int minHessian = ;

   SurfFeatureDetector detector( minHessian );

   std::vector<KeyPoint> keypoints_1, keypoints_2;

   detector.detect( img_1, keypoints_1 );

   detector.detect( img_2, keypoints_2 );

   //-- Step 2: Calculate descriptors (feature vectors)

   SurfDescriptorExtractor extractor;

   Mat descriptors_1, descriptors_2;

   extractor.compute( img_1, keypoints_1, descriptors_1 );

   extractor.compute( img_2, keypoints_2, descriptors_2 );

   //-- Step 3: Matching descriptor vectors with a brute force matcher

   BruteForceMatcher< L2<float> > matcher;

   std::vector< DMatch > matches;

   matcher.match( descriptors_1, descriptors_2, matches );

   //-- Draw matches

   Mat img_matches;

   drawMatches( img_1, keypoints_1, img_2, keypoints_2, matches, img_matches );

   //-- Show detected matches

   imshow("Matches", img_matches );

   waitKey();

   return ;

   }

  /** @function readme */

  void readme()

  { std::cout << " Usage: ./SURF_descriptor <img1> <img2>" << std::endl; }