Approximate Entropy Calculation for an Image

Hi,

How can we compute the APPROXIMATE ENTROPY of an IMAGE.

Please help,

Thanks

Answer 1

[Thorsten]

function E = entropy(I)
% Assume I in the range 0..1
p = hist(I(:), linspace(0,1,256));  % create histogram
p(p==0) = []; % remove zero entries that would cause log2 to return NaN
p = p/numel(I); % normalize histogram to unity
E = -sum(p.*log2(p)); % entropy definition

[shishir]

This is for computing the ENTROPY. But I want to compute SAMPLE ENTROPY and APPROXIMATE ENTROPY of an IMAGE.

So if you give me something regarding the described entropies, it would be great help.

Thank You Sir,

[Thorsten]

Have a look at http://www.mathworks.com/matlabcentral/fileexchange/35784-sample-entropy

[Marcus Tan]

Can someone guide me also how to calculate the approximate entropy of an Spectrogram image transformed from EEG signal? I have seen number of file exchange but none of them work.