calculate psd using fft2 for 2-D matrix

I am trying to calculate the PSD using fft2 for 2D matrix, but I am not sure how to calculate the PSD from fft2

I have used the following lines when calculating the PSD for pressure time history data (p) using fft (1-D fast fourier transform)

fs=1/delta_t;
n = length(p);
FFT = fft(p);
FFT= FFT(1:n/2+1);
psd1 = 2*abs(FFT).^2/(n*fs);
f = fs*(0:(n/2))/n;

In case of having the pressure time history as 2-D array, I used fft2 but I not not sure how to calculate PSD

fs=1/delta_t;
nx=size(p,1);
ny=size(p,2);
FFT=fft2(p);
FFT=FFT(1:nx/2+1,1:ny/2+1);
psd1= 2*abs(FFT).^2/(nx*fs*ny*fs);
fx= fs*(0:(nx/2))/nx;
fy= fs*(0:(ny/2))/ny;