Absolute Moment Block Truncation Coding (AMBTC)- MATLAB Code

Here is the matlab code.. Cheers !!

%AMBTC
%Ref:Lema, M., and O. Mitchell.
%”Absolute moment block truncation coding and its application to color images.”
% IEEE Transactions on communications 32.10 (1984): 1148-1157.

%Programmed By: Sankarasrinivasan S
%Multimedia Signal Processing Lab, Dept. of Elec Engg. NTUST
%Oct 2016

function [H]=ambtc(in,bs)

%in–> input image; bs–> blocksize
[s1 s2]=size(in);

n=bs*bs;

for i=1:bs:s1
for j=1:bs:s2
bl=in(i:i+(bs-1),j:j+(bs-1));
mn=mean(mean(bl)) ; %Computing Mean
fm=mean(mean(abs(bl-mn))) ; %Abs moment
g=(n*fm)/2;
c=bl>mn;
q=nnz(c);
if(q==n)
b=mn;
a=0;
else
b=mn+(g/q);
a=mn-(g/(n-q));
end
out=round(c.*b+(~c).*a);
H(i:i+(bs-1),j:j+(bs-1))=out;
end
end

%To Validate Paper Results
% test=[121 114 56 47; 37 200 247 255; 16 0 12 169; 43 5 7 251;];
% mn =
% 98.7500
% fm =
% 83.2188
% g =
% 665.7500
% b =
% 193.8571
% H =
% 194 194 25 25
% 25 194 194 194
% 25 25 25 194
% 25 25 25 194