Open In App

Gaussian Filter Generation in C++

Last Updated : 11 Sep, 2023
Improve
Improve
Like Article
Like
Save
Share
Report

Gaussian Filtering is widely used in the field of image processing. It is used to reduce the noise of an image. In this article we will generate a 2D Gaussian Kernel. The 2D Gaussian Kernel follows the below given Gaussian Distribution. 
G(x, y)=\frac{1}{2\pi \sigma ^{2}}e^{-\frac{x^{2}+y^{2}}{2\sigma ^{2}}}
Where, y is the distance along vertical axis from the origin, x is the distance along horizontal axis from the origin and ? is the standard deviation.

Implementation in C++ 

C++

// C++ program to generate Gaussian filter
#include <cmath>
#include <iomanip>
#include <iostream>
using namespace std;
  
// Function to create Gaussian filter
void FilterCreation(double GKernel[][5])
{
    // initialising standard deviation to 1.0
    double sigma = 1.0;
    double r, s = 2.0 * sigma * sigma;
  
    // sum is for normalization
    double sum = 0.0;
  
    // generating 5x5 kernel
    for (int x = -2; x <= 2; x++) {
        for (int y = -2; y <= 2; y++) {
            r = sqrt(x * x + y * y);
            GKernel[x + 2][y + 2] = (exp(-(r * r) / s)) / (M_PI * s);
            sum += GKernel[x + 2][y + 2];
        }
    }
  
    // normalising the Kernel
    for (int i = 0; i < 5; ++i)
        for (int j = 0; j < 5; ++j)
            GKernel[i][j] /= sum;
}
  
// Driver program to test above function
int main()
{
    double GKernel[5][5];
    FilterCreation(GKernel);
  
    for (int i = 0; i < 5; ++i) {
        for (int j = 0; j < 5; ++j)
            cout << GKernel[i][j] << "\t";
        cout << endl;
    }
}

                    

Output: 

0.00296902    0.0133062    0.0219382    0.0133062    0.00296902    
0.0133062    0.0596343    0.0983203    0.0596343    0.0133062    
0.0219382    0.0983203    0.162103    0.0983203    0.0219382    
0.0133062    0.0596343    0.0983203    0.0596343    0.0133062    
0.00296902    0.0133062    0.0219382    0.0133062    0.00296902


References: 
https://en.wikipedia.org/wiki/Gaussian_filter


 



Similar Reads

Article Tags :