I have been attempting to calculate the spatial frequency of a colour image.

I first converted it to grayscale and used a Fast Fourier transformation (fft2) that codes the quantity of each spatial frequency in the image in MATLAB. This provides a matrix of coefficients representing the amount of each spatial frequency and orientation and its phase.

I’m having difficulty translating this matrix into a spatial frequency value that I can use to describe the spatial frequency of the image in cycles per image. Also, how can I plot the fft in a way that shows the cycles?

Do you have any suggestions to point me in the right direction?

  • $\begingroup$ fftshift , then , imshow(log10(abs(fftshif)) $\endgroup$ – MimSaad Jun 21 '17 at 19:11

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