I'd like to make PSF i.e. Point spread function to an image I am using python, if any one can help me and tell me the idea or the mechanism to code it in python?

I tried FFT2 via OpenCV, then via numpy and lastly via Scipy with fftpack, but I can't solve the problem.

Is it true that to make a PSF to an image:

I have to get the coefficients of an image then do FFT2 then take the absolute value for the new coefficient i.e. fft2 coefficients and lastly power them all by two?