fftshift in frequency filtering

Does it mandatory to shift the frequency components using fftshift for a fourier transformed image before applying lowpass or gaussian LPF?

Cant we directly perform frequency filtering without using fftshift of fft image.

can anyone explain me the difference? thanks in advance

Answer 1

[Stephen]

I would imagine that you could directly apply low pass, but I don't really know. This is an interesting question. What happened when you tried doing it?