Fault in result in formula

Hello, I want implement this formula . but i think it give me fault result. For example : X = 156 and Pmn should be .0540 but with matlab give me .0059

input = imread('cameraman.tif');
[m , n] = size(input);
output = zeros(m,n);
L = 256;
Xmax = L - 1 ; 
Fe = 2;
Fd = 30;
Pmn = zeros(m,n);
Pmn = double(Pmn);
for i = 1:m
    for j = 1:n
        Xmn = double(input(i,j));
        Pmn(i,j)=1/((1+((Xmax-Xmn)/Fd)).^Fe);
    end
end

[Stefan Raab]

Hello,

I cannot reproduce your error. If I set m=1, n=1 and input=156, then MATLAB calculates the correct result Pmn = P11 = 0.0540832.... Here my code, I changed only the input:

n = 1;
m = 1;
input = 156;
output = zeros(m,n);
L = 256;
Xmax = L - 1 ; 
Fe = 2;
Fd = 30;
Pmn = zeros(m,n);
Pmn = double(Pmn);
for i = 1:m
  for j = 1:n
      Xmn = double(input(i,j));
      Pmn(i,j)=1/((1+((Xmax-Xmn)/Fd)).^Fe);
  end
end