How to find maximum frequency of a 2D image after fourier transform?

Hi,

I have a 2D grayscale image I, and I've done fourier transform using fft, with center shifted (fftshift). I want to find the maximum frequency of the image. Are there any way to do this?

[KSSV]

Read about max

[Ziwei Liu]

I'm trying to find the max frequency, not the one with max magnitude

Answer 1

[Walter Roberson]

maximum frequency is max(size(TheImage))/2

In theory the coefficient associated with that frequency could be 0, but it is unlikely to be 0.