MATLAB: Estimation/measure of entropy

entropy

How to calculate entropy of an image without using the inbuilt functions? Entropy is the measure of loss of information.

-summation(P.*log2 P)

P is the count of histogram..but not getting the proper result!Anyone plz help.

Best Answer

Make sure you run log2 only on values > 0. Otherwise you would get NaN.

I = im2double(rgb2gray(imread('peppers.png')));
P = hist(I(:), linspace(0, 1, 256)); P = P(:); P = P(P(:)>0);
E = -sum(P.*log2(P))

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MATLAB: Approximate Entropy Calculation for an Image

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

MATLAB: How to write a function which gives me entropy using discrete probability distribution as input.thanks in advance

entropy = @(P) -sum(P.*log2(P))

Best Answer

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MATLAB: Approximate Entropy Calculation for an Image

MATLAB: How to write a function which gives me entropy using discrete probability distribution as input.thanks in advance

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