function [hd]= histo(inputfilea,inputfileb);
data1 = imread(inputfilea);
data2 = imread(inputfileb);
ndata1 = imhist(data1);
ndata2 = imhist(data2);
hd = 0;
for i = 1:256
    datasum = sqrt((ndata1(i,:)-ndata2(i,:))*(ndata1(i,:)-ndata2(i,:)));
    hd = hd+datasum;
end
%N = hist(A,M)
return;
