这段简介可以描述为:MATLAB中的互信息源代码提供了一套用于计算两个随机变量之间统计依赖性的高效工具和函数,适用于信号处理、图像分析及机器学习等领域的研究与开发。
function mi = MI(a,b)
% 计算a和b在重叠部分的互信息(Mutual Information, MI)
[Ma,Na] = size(a);
[Mb,Nb] = size(b);
M=min(Ma,Mb);
N=min(Na,Nb);
% 初始化直方图数组
hab = zeros(256,256);
ha = zeros(1,256);
hb = zeros(1,256);
% 归一化处理
if max(max(a))~=min(min(a))
a = (a-min(min(a)))/(max(max(a))-min(min(a)));
else
a = zeros(M,N);
end
if max(max(b))-min(min(b))
b = (b-min(min(b)))/(max(max(b))-min(min(b)));
else
b = zeros(M,N);
end
a = double(int16(a*255))+1;
b = double(int16(b*255))+1;
% 统计直方图
for i=1:M
for j=1:N
indexx = a(i,j);
indexy = b(i,j) ;
hab(indexx,indexy) = hab(indexx,indexy)+1; % 联合直方图
ha(indexx) = ha(indexx)+1; % a图直方图
hb(indexy) = hb(indexy)+1; % b图直方图
end
end
% 计算联合信息熵
hsum = sum(sum(hab));
index = find(hab~=0);
p = hab/hsum;
Hab = sum(-log(p(index)).*(p(index)));
% 计算a图的信息熵
hsum = sum(ha);
index = find(ha~=0);
p = ha/hsum;
Ha = -sum(log(p(index)).*p(index));
% 计算b图信息熵
hsum = sum(hb);
index = find(hb~=0);
p = hb/hsum;
Hb = -sum(log(p(index)).*p(index));
% 计算a和b的互信息
mi = Ha+Hb-Hab;
%计算归一化互信息(注释掉了,原文中未给出具体公式)
% mi = hab/(Ha+Hb);