其中,AB聯合概率分佈和關於A和關於B的邊緣概率分佈都可以由聯合直方圖歸一化獲得。
Matlab實現代碼如下:
(1)圖像的熵
function shang = ssshang(X)
[m,n,t]=size(X); I3 = double(X)+1;
s(256) = 0;
for i = 1:m
for j = 1:n
va = I3(i,j);
s(va) = s(va)+1;
end
end
p = s./(m*n);
en = 0.;
for i = 1:256
if p(i)~=0
en = en+p(i)*log2(p(i));%概率取對數(以2爲底)再乘以概率 最後連加取反
end
end
shang = -en;
(2)兩幅圖像的聯合熵
function abshang = ssshangab(X,Y)
[m,n,t]=size(X); a = double(X)+1;
b = double(Y)+1;
hab=zeros(256,256);
for i = 1:m
for j = 1:n
index_x=a(i,j);
index_y=b(i,j);
hab(index_x,index_y)=hab(index_x,index_y)+1;
end
end
p = hab./(m*n);
en = 0.;
for i = 1:256
for j = 1:256
if p(i,j)~=0
en = en+p(i,j)*log2(p(i,j));%概率取對數(以2爲底)再乘以概率 最後連加取反
end
end
end
abshang = -en;
(3)兩幅圖像的互信息
MI = HA + HB - HAB
參考文章:http://www.ilovematlab.cn/thread-45649-1-1.html