LPF in frequency domain

clc; close all; clear

img = imread('PUPPY.jpg');

low_mask=zeros(M,N);

low_mask(M/2 - M/8:M/2 + M/8,N/2 - N/8:N/2 + N/8)=1; % DC+-16 pix : Low

LPF_img = ;%

How to make lpf image in frequency domain using this code ?

please .................

I don't know ....

Answer 1

[Gokul Nath S J]

Hi Manda,

I am assuming LPF to Low pass filtering in digital Image processing. Please find the following code as an extension. I have converted an rgb image to grayscale assuming that you are having a colour image. If not kindly skip this step.

clc; close all; clear;
img = imread(‘PUPPY.jpg’);
imgGray = rgb2gray(img);
[M, N] = size(imgGray);
low_mask=zeros(size(imgGray));
low_mask(M/2 - M/8:M/2 + M/8,N/2 - N/8:N/2 + N/8)=1; % DC+-16 pix : Low
LPF_img = fft(imgGray) .* (low_mask);%
Filt_img = ifft(LPF_img);
imshow(abs(Filt_img),[]);

In the 7th line, I am doing a frequency domain multiplication (time domain convolution) between the images. Finally in line 8, I did an inverse Fourier transform to convert the image from frequency domain to the spatial one.

Hope this helps!