1/f amplitude frequency plot

I'm running an image analysis using fourier transform.

I want to use spectral amplitude as a measure of naturalness of an image.

It is said that the i/f amplitude-frequency scaling is modulated by the naturalness of scenes, with steeper slops for naturalistics compared to artifactual scenes.

I just want to run this in matlab and test on two images, naturalistic and artifactual to see how it is.

Please share a simple code to read an image and run this 1/f amplitude - frequency scaling.

I'm here so far:

clear all; close all; clc

imdata = imread('C:\....\ab.jpg');

figure(1);imshow(imdata); title('Original Image');

imdata = rgb2gray(imdata);

figure(2); imshow(imdata); title('Gray Image');

%get fourier transform of an image

F = fft2(imdata);

%fourier transform of an image

S = abs(F);

figure(3);imshow(S,[]);title('Fourier Transform of an Image');

%get the centered spectrium

Fsh = fftshift(F);

figure(4);imshow(abs(Fsh),[]);title('Centered Fourier Transform of Image')

%apply log transform

S2 = log(1+abs(Fsh));

figure(5);imshow(S2,[]);title('log transformed image')

%reconstruct our image

F = ifftshift(Fsh);

f =ifft2(F);

figure(6);imshow(f,[]),title('reconstruct image')

If I'm missing something, too, please explain how to go about it.