#3b: Detecting Vertical and Horizontal Edges

Prerequisites:

• #3a Tutorial
• Convolution in 2D. Sources: Here. Example.
• filter2D Documentation

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#include
#include
#include
using namespace std;
using namespace cv;
int main()
{

 Mat img_v, img_h,img=imread("images/black.jpg");

 float vertical_fk[5][5]={{0,0,0,0,0},{0,0,0,0,0},{-1,-2,6,-2,-1},{0,0,0,0,0},{0,0,0,0,0}};
 float horizontal_fk[5][5]={{0,0,-1,0,0},{0,0,-2,0,0},{0,0,6,0,0},{0,0,-2,0,0},{0,0,-1,0,0}};
 Mat filter_v=Mat(5,5,CV_32FC1, vertical_fk);
 Mat filter_h=Mat(5,5,CV_32FC1, horizontal_fk);


 filter2D(img,img_v,-1,filter_v);
 filter2D(img,img_h,-1,filter_h);

 namedWindow("Image");
 namedWindow("Image_V");
 namedWindow("Image_H");

 imshow("Image",img);
 imshow("Image_V",img_v);
 imshow("Image_H",img_h);
 while(char(waitKey(0))!='q'){}
 return 0;

}

Results:

Cool, isn't it?

It would be more clear if go through the documentation of the functions you've learnt.

Still, if you have any doubts, feel free to comment.