function MI=MI(vec1,vec2)
a=joint_h(vec1,vec2); % calculating joint histogram for two images
[r,c] = size(a);
b= a./(r*c); % normalized joint histogram
y_marg=sum(b); %sum of the rows of normalized joint histogram即每一列所有元素的和，结果为一个行向量
x_marg=sum(b');%sum of columns of normalized joint histogran
Hy=0;
for i=1:c; % col505
if( y_marg(i)==0 )
%do nothing
else
Hy = Hy + -(y_marg(i)*(log2(y_marg(i)))); %marginal entropy for image 1
end
end
Hx=0;
for i=1:r; %rows
if( x_marg(i)==0 )
%do nothing
else
Hx = Hx + -(x_marg(i)*(log2(x_marg(i)))); %marginal entropy for image 2
end
end
h_xy = -sum(sum(b.*(log2(b+(b==0))))); % joint entropy
% if method=='Normalized'
MI = (Hx + Hy)/h_xy;% Mutual information
% else
% MI = Hx + Hy - h_xy;% Mutual information
% end
[p12, p1, p2] = estpab(vec1,vec2);
MI = estmutualinfo(p12,p1,p2);
