function [hd]= histo(filea,fileb);
A = imread(filea);
B = imread(fileb);
M = imhist(A);
N = imhist(B);
hd = 0;
for i = 1:256
    sum = sqrt((M(i,:)-N(i,:))*(M(i,:)-N(i,:)));
    hd = hd+sum;
end
%N = hist(A,M)
return;
