计算遥感图像各个波段的信息熵

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%%%% 计算遥感图像的各个波段的信息熵%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%

function outval = entropy(img)

A=imread(img);

[M,N,b]=size(A);

A = double(A);

%生成值为零的初始化数组。其用来统计和存储对应于每个%灰度级的频数（概率），数组的大小根据图像的大小而定Result=zeros(1,b);

%figure,imshow(A);

for k = 1 : b

band = A(:,:,k);

temp=zeros(M,N);

%对图像的灰度值做统计，计算每个灰度级出现的次数

for m=1:M;

for n=1:N;

if band(m,n)==0;

i=1;

else

i=band(m,n);

end

temp(i)=temp(i)+1;

end

end

temp=temp./(M*N);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%% 由熵的定义做计算信息熵%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

for i=1:length(temp)

if temp(i)==0;

Result(k)=Result(k);

else

Result(k)=Result(k)-temp(i)*log2(temp(i));

end

end

end

outval = Result;