frequencies from fft2 matrix

Hi guys! I have a matrix that results from fft2 [matrix(f1,f2)]. I would like to take (from the matrix) values with frequencies between an interval, for example: x = find(f1 < 0.5 & f1 > 0.05) y = find(f2 < 0.5 & f2 > 0.05) How can I get it? Thank you!

Answer 1

[Dr. Seis]

Take a look at my post here: http://www.mathworks.com/matlabcentral/answers/24965-fft2-function-in-matlab

The example I show assumes that if you take the 2D Fourier transform of an MxN matrix that both M and N are divisible by two. If either M or N are odd, then the definitions of the frequency ranges will have to be defined differently. Around the part where I start plotting stuff, I compute the 2D FFT using Matlabs fft2 and I use fftshift to be able to plot it according to the frequency ranges I define earlier.

Let me know if you have any questions.