Histogram deviation or MDMF

I am trying to calculate the histogram deviation(H.D) or Maximum Deviation Measuring Factor(M.D.M.F) as mentioned in

Histogram Deviation (HD) and

Maximum Deviation Measuring Factor

Two coding,I have done.one is

clear all
close all
clc
plain = imread('lena.bmp');% Read the input image
[M N] = size(plain);
r = uint8(randi([0,256],M,N)); % Generate a random matrix for encryption
cipher = bitxor(plain,r); % Encryption
% x = double(plain);
% y = double(cipher);
x = plain;
y = cipher;
x1 = imhist(x);
y1 = imhist(y);
%then calculate the difference between the two
diff = abs(x1-y1);
%then calculate D as follows
D1 = 0;
for i = 2:255
D1 = D1+diff(i);
end;
D2 = (diff(1)+diff(256))/2;
MDMF = D1+D2/(M*N)

and the other is

clear all
close all
clc
plain = imread('lena.bmp');% Read the input image
[M N] = size(plain);
r = uint8(randi([0,256],M,N)); % Generate a random matrix for encryption
cipher = bitxor(plain,r); % Encryption
% x = double(plain);
% y = double(cipher);
x = plain;
y = cipher;
hi = imhist(x);
hr = imhist(y);
subplot(211)
imhist(x);
title('Histogram of Original Image')
subplot(212)
imhist(y);
title('Histogram of Encrypted Image')
 diff = imabsdiff(hi,hr);
% z = abs(hi-hr);
d = ((diff(1)+diff(256))/2);
d1 = sum(diff(2:255));
histogram_deviation = (d+d1)/(256*256)

Please help me to identify which code is correct according to the theoretical concepts