How to calculate the entropy of a portion of image as in the following formula?
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Hello everyone, I am new here on matlab. I should calculate the subset entropy of portion of image, defined as in the formula (4). Could someone please tell me how to write a routine that calculates the subset entropy using matlab please.
Thank you very much in advance.
Accepted Answer
Bruno Luong
on 20 Jan 2023
Please try this
A=imread('ngc6543a.jpg');;
A=double(A(1:500,:,:));
A=sum(A,3);
M = 11; N = 11;
% Build 8-neighbor
[di,dj] = ndgrid(-1:1);
di = di(:);
dj = dj(:);
di(5,:) = []; dj(5,:) = []; % remove (0,0) shift
A8 = zeros([size(A),8]);
for i=1:8
A8(:,:,i) = A(min(max(di(i)+(1:end),1),end), ...
min(max(dj(i)+(1:end),1),end));
end
dA = sum(abs(A8-A),3);
depth = 24+zeros(size(A));
K = ones(M,N);
delta = conv2(dA,K,'same')./(2.^depth.*conv2(ones(size(dA)),K,'same'));
subplot(2,1,1);
imagesc(A)
colormap gray
subplot(2,1,2);
imagesc(delta);
7 Comments
Bruno Luong
on 20 Jan 2023
Edited: Bruno Luong
on 20 Jan 2023
Ask people who claim it, here my value is smal becaise the depth (beta) is 24 as in your example of code.
1/2^24
You have all the values in my code, why can't you check it.
I simply implement what you wrote above as formula, I don't know this specific formula, the paper and people who wrote it.
What I know is entropy never have strict unit definition, as long as it's defined consistently across the usage for comparison.
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