How to transform an gray scale image from frequency to spatial domain ?

I can transform a gray scale image from spatial domain to frequency domain. But when i transform that image form frequency to spatial domain using ifft() its not giving me the real image. What should i do?

Here is my code:

img = imread('sample.tif');
imgFFT = fft2(double(img));
img2 = ifft2(imgFFT);

I just want to simply transform an image to frequency domain and then re-transform it into original image. But that ifft2() function is not giving me the original image.

Answer 1

[John D'Errico]

Seems to work for me.

A = magic(10);
Af = fft2(A);
Ai = ifft2(Af);

norm(A - Ai)
ans =
   3.3779e-14

[John D'Errico]

My guess is the OP simply tested to see if the result was EQUAL to the start. Of course not. It will be in error, just as my test was. That does not make it different, just floating point trash.

[Ruhul Amin]

Thanks for your response. Its working. I don't no why i getting wrong answer that time.. :)

img = imread('sample.TIF');
figure,imshow(img,'InitialMagnification','fit');
imgB = im2bw(img,0.2);                                                      
figure,imshow(imgB,[],'InitialMagnification','fit');
imgF = fftshift(fft2(imgB));
figure, imshow(imgF,[],'InitialMagnification','fit');
imgIF = ifft2(ifftshift(imgF));
figure, imshow(imgIF,[],'InitialMagnification','fit');

It's working perfectly.

Answer 2

[Image Analyst]

This works fine for me:

grayImage = imread('cameraman.tif');
% Display the original gray scale image.
subplot(1, 2, 1);
imshow(grayImage, []);
title('Original Grayscale Image', 'FontSize', fontSize, 'Interpreter', 'None');

% Set up figure properties:
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0 0 1 1]);
% Get rid of tool bar and pulldown menus that are along top of figure.
set(gcf, 'Toolbar', 'none', 'Menu', 'none');
% Give a name to the title bar.
set(gcf, 'Name', 'Demo by ImageAnalyst', 'NumberTitle', 'Off') 

imgFFT = fft2(double(grayImage));
roundTripImage = ifft2(imgFFT);
whos roundTripImage
subplot(1, 2, 2);
imshow(roundTripImage, []);
title('After round trip to Fourier Domain', 'FontSize', fontSize, 'Interpreter', 'None');

How is your image different? Please attach sample.tif. What is it? Is it not gray scale? Is it color? Perhaps that might mess it up.

[Ruhul Amin]

Thanks its working. :) But now i am facing different problem. :( I have an gray scale image and i want to remove some objects of that image in frequency domain. But i don't know how to do it. :(

[Image Analyst]

Sorry, it can't be done. Is someone telling you it can? Actually here's one sure-fire effective method:

imgFFT = zeros(size(grayImage));
roundTripImage = ifft2(imgFFT);

[Sudeepto Mohanta]

Can you please explain this code?

It will be very helpful and understandable.

[Image Analyst]

fft2() takes the 2-D fft of the image.

subplot(1, 2, n) takes a figure and has 1 row and 2 columns of plots (axes for images). n is the plot/image slot that the image goes into.

imshow() shows the image in the designated slot.

title() puts words above the image.

whos tells you information about the variable.

imread() reads in an image from disk, given a filename.

[Sudeepto Mohanta]

thanks a lot.

Answer 3

[Nehal fawzy]

any one help me

how i can transform image from spatial domain to neutrosophic domain with matlab code