Magnitude not showing up

Hey everyone, I found this code on a website and a simplified version is:

 %2D FFT Demo
close all;
clear all;
 %Import images 
 imageA = imread('greekchurch.jpg');

 %Display images 
 figure, imshow(imageA)
 title('Image A - Greek Church')

 %Perform 2D FFTs 
 fftA = fft2(double(imageA));

 %Display magnitude and phase of 2D FFTs
 figure, imshow(abs(fftshift(fftA)),[24 100000]), colormap gray
 title('Image A FFT2 Magnitude')

When I run it, the image output is white. Anyone know whats wrong?

Answer 1

[Image Analyst]

Try

imshow(abs(fftshift(fftA)),[]);

Or, to compress the scale,

imshow(log(abs(fftshift(fftA))), []);

[u-will-neva-no]

Thanks for the reply. Unfortunately, neither of the above worked. This is very strange...

[Image Analyst]

Your DC component is probably so huge you don't see it. Try this code and see a working version:

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
imtool close all;  % Close all imtool figures.
clear;  % Erase all existing variables.
workspace;  % Make sure the workspace panel is showing.
format longg;
format compact;
fontSize = 20;

%2D FFT Demo
%Import images
myImage = imread('cameraman.tif');
[rows columns numberOfColorChannels] = size(myImage)
if numberOfColorChannels > 1
  myImage = rgb2gray(myImage);
end

%Display images
subplot(2, 2, 1);
imshow(myImage)
title('Original Gray Scale Image', 'FontSize', fontSize)

%Perform 2D FFTs
fftA = fft2(double(myImage));
shiftedFFT = fftshift(fftA);
subplot(2, 2, 2);
imshow(real(shiftedFFT));
title('Real Part of Spectrum', 'FontSize', fontSize)
subplot(2, 2, 3);
imshow(imag(shiftedFFT));
title('Imaginary Part of Spectrum', 'FontSize', fontSize)

%Display magnitude and phase of 2D FFTs
subplot(2, 2, 4);
imshow(log(abs(shiftedFFT)),[]);
colormap gray
title('Image A FFT2 Magnitude');
title('Log Magnitude of Spectrum', 'FontSize', fontSize)
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);

[u-will-neva-no]

Perfect. Thanks so much!

Answer 2

[Yusef]

I had the same problem, just need

I=imread('image.bmp');
I = rgb2gray(I);
fftA = fft2(double(I));