The question of FFT

[Yao-Wang Li]

Dear all,

For a real function, for example, an image (u), Its Fourier transform
should follow the Friedel symmetry, I mean the U(s) = U*(-s). Here,
U(s) is the Fourier transform of u, and is a complex number. U*(s) is
its conjugate. I tested two images in imagej, and it works. However, it
is not happen in Octave, the real part is not equal and the imaginary
part is not opposite. They should have the magnitude and opposite
phase. That is what is my question. that is what I did in Octave.


img1=imread("fibers01.tif");
img2=imread("fibers02.tif");

%Fourier transform
img1_sf=fft2(double(img1));
img2_sf=fft2(double(img2));



Thank you very much. 



Best Regards,

Yaowang