How much should you zero pad an image before taking the fft ?

If i have an image that is 200x200 and I want to take the FFT how much zero padding is required ?

[David Goodmanson]

Hi raheem, for what purpose might you want to use zero padding?

[raheem mian]

To calculate a phase correlation

Answer 1

[Bhargavi Maganuru]

If input signal of fft is not in the powers of 2, which is 200 in your case so, you can do zero padding till length is 256.

[David Goodmanson]

HI Bhargavi,

could you explain why going to a power of 2 is a good idea, or not?