# Gaussian Filter generation using C/C++

Gaussian filtering is extensively used in Image Processing to reduce the noise of an image. In this article I will generate the 2D Gaussian Kernel that follows the Gaussian Distribution which is given

Where σ is the standard deviation of distribution

*, x*is the distance from the origin in the horizontal axis,*y*is the distance from the origin in the vertical axis. The mean is assumed to be at origin O(0,0). The pictorial view of Gaussian Distribution for σ= 0 and mean at origin is**Source Code in C/C++**

#include <iostream> #include <cmath> #include <iomanip> using namespace std; void createFilter(double gKernel[][5]) { // set standard deviation to 1.0 double sigma = 1.0; double r, s = 2.0 * sigma * sigma; // sum is for normalization double sum = 0.0; // generate 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]; } } // normalize the Kernel for(int i = 0; i < 5; ++i) for(int j = 0; j < 5; ++j) gKernel[i][j] /= sum; } int main() { double gKernel[5][5]; createFilter(gKernel); for(int i = 0; i < 5; ++i) { for (int j = 0; j < 5; ++j) cout<<gKernel[i][j]<<"\t"; cout<<endl; } }

**Output 5×5 Gaussian Kernel**

**References:**

Thanks for your Blog entry, nice Example.

cool, thanks for sharing.

Look carefully i have write r*r in the formula. This answer was verified using MATLAB's Gaussian function

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Hi!

What is the reason to sqrt and then do r*r? Why not just skip the sqrt and only use r?

Thanks a lot!

hi

i need source code in c++ to apply gaussian filter to gray image

i need code in c++ for apply gaussian filter to gray image