Converting an image to frequency response

Sir, i want to convert a 2D image into its corresponding frequency plot. I tried this code but it is giving a blank graph for all the images.

I= imread('abc.jpg');
grayImage = rgb2gray(I);
subplot(1,2,1);
imshow(grayImage);
axis on;
ft = fftshift(log(abs(fft2(grayImage))));
subplot(1,2,2);
imshow(ft, []);
axis on;

[gulu]

Thank u for your help.. but is there any other way than using fft to plot the signal of an image. I will be thankful for your help.

[Image Analyst]

You can use pwelch but I think that may need a 1D signal. Why do you need a different method?

Answer 1

[Image Analyst]

See my attached demos. If you still have problems, write back.