# what is the wrong in this code?

2 views (last 30 days)
Ahmed Grera on 5 Sep 2017
Commented: Ahmed Grera on 6 Sep 2017
clc
clear all
close all
A = fftshift(fft2(lena));
S = imnoise(lena,'Gaussian',0,1);
size(S)
% define spatial filters
h_gauss= fspecial('gaussian', 15, 1.0);
% results after spatial filtering
lena_h_gauss = imfilter(S, h_gauss, 'replicate');
% fourier transformed filters
H_gauss = fftshift(fft2(lena_h_gauss));
size(H_gauss)
% filtering in frequency domain
Lena_H_gauss = S .* H_gauss;
lena_H_gauss = ifft2(ifftshift(Lena_H_gauss));
% print results
subplot(3,3,1); imshow(lena); title('Original Image');
subplot(3,3,2); imshow(lena_h_gauss); title('Gauss-Filtered Image');
subplot(3,3,3); imshow(real(log(Lena)), []); title('FT (Original Image)');
subplot(3,3,4); imshow(real(log(H_gauss)), []); title('FT (Gauss Filter)');
subplot(3,3,5); imshow(lena_H_gauss); title('Result FT Gauss');

Image Analyst on 5 Sep 2017
S is complex and imfilter() doesn't work on complex images. You might have to work on the real and imaginary images one at a time.

John BG on 6 Sep 2017
Edited: John BG on 6 Sep 2017
Hi Ahmed
1.
it may be that rather than real an imaginary parts, you may consider using the module, with abs
Lena_H_gauss = S .* H_gauss;
use
lena_H_gauss = S .* uint64(abs(H_gauss));
2.
there are
lena_h_gauss
and
Lena_h_gauss
probably only one should be used
3.
subplot(3,3,1); imshow(lena); title('Original Image');
subplot(3,3,2); imshow(lena_h_gauss); title('Gauss-Filtered Image');
subplot(3,3,3); imshow(real(log(Lena)), []); title('FT (Original Image)');
subplot(3,3,4); imshow(real(log(H_gauss)), []); title('FT (Gauss Filter)');
subplot(3,3,5); imshow(lena_H_gauss); title('Result FT Gauss');
use
subplot(3,3,1); imshow(lena); title('Original Image');
subplot(3,3,2); imshow(lena_h_gauss); title('Gauss-Filtered Image');
subplot(3,3,3); imshow(real(log(double(lena))), []); title('FT (Original Image)');
subplot(3,3,4); imshow(real(log(double(H_gauss))), []); title('FT (Gauss Filter)');
subplot(3,3,5); imshow(lena_H_gauss); title('Result FT Gauss');
.
John BG
Ahmed Grera on 6 Sep 2017
Hi Jhon
There is still an error going on
lena_H_gauss = S .* uint64(abs(H_gauss));

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