test.cpp

#include<iostream>
#include<cmath>
#include<opencv2/imgproc/imgproc.hpp>
#include<opencv2/highgui/highgui.hpp>

using namespace std;
using namespace cv;


// Computes the x component of the gradient vector
// at a given point in a image.
// returns gradient in the x direction
int xGradient(Mat image, int x, int y)
{
    return image.at<uchar>(y-1, x-1) +
                2*image.at<uchar>(y, x-1) +
                 image.at<uchar>(y+1, x-1) -
                  image.at<uchar>(y-1, x+1) -
                   2*image.at<uchar>(y, x+1) -
                    image.at<uchar>(y+1, x+1);
}

// Computes the y component of the gradient vector
// at a given point in a image
// returns gradient in the y direction

int yGradient(Mat image, int x, int y)
{
    return image.at<uchar>(y-1, x-1) +
                2*image.at<uchar>(y-1, x) +
                 image.at<uchar>(y-1, x+1) -
                  image.at<uchar>(y+1, x-1) -
                   2*image.at<uchar>(y+1, x) -
                    image.at<uchar>(y+1, x+1);
}

int main()
{

      Mat src, dst;
      int gx, gy, sum;

      // Load an image
      src = imread("coins1.png", CV_LOAD_IMAGE_GRAYSCALE);
      dst = src.clone();
      if( !src.data )
      { return -1; }


        for(int y = 0; y < src.rows; y++)
            for(int x = 0; x < src.cols; x++)
                dst.at<uchar>(y,x) = 0.0;

        for(int y = 1; y < src.rows - 1; y++){
            for(int x = 1; x < src.cols - 1; x++){
                dst.at<uchar>(y,x) = yGradient(src, x, y);
            }
        }

        imwrite("testy.jpg", dst);

      waitKey();


    return 0;
}