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how to compare ground truth image with segmented image?

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tashu Dabariya
tashu Dabariya on 29 Jul 2019
BW2=imread('C2.png'); %segmented image
figure,imshow(BW2)
BW=imread('001_mask.png'); %groundtruth-image
figure,imshow(BW)
% mask = false(size(BW2));
% mask(25:end-25,25:end-25) = true;
% BW = activecontour(BW2, mask, 300);
similarity = jaccard (BW2, BW)
figure
imshowpair(BW2, BW)
title(['Jaccard Index = ' num2str(similarity)])
I am trying to find accuracy but got an error.
Undefined function 'jaccard' for input arguments of type 'uint8'.
Error in Untitled (line 8)
similarity = jaccard (BW2, BW)
what will be changed in this code?

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Adam
Adam on 29 Jul 2019
Do you have the Image Processing Toolbox and are you using R2017b or later (it does help a lot if you fill in the Products and Release section of the question)? What does
which jaccard
show?
Arslan Ahmed Awan
Arslan Ahmed Awan on 22 Oct 2019
You have to Install MATLAB R2017b because jaccard was introduced in Image Processing Toolbox of R2017b.

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Answers (2)

Constantino Carlos Reyes-Aldasoro
Jaccard index is the intersection (BW.*BW2) over the union (BW|BW2) or ((BW+BW2)>0), so you can calculate directly like this
sum(sum( BW.*BW2)) / sum(sum( BW|BW2))
Accuracy is different, that is how many pixels are exactly the same (including background)
sum(sum(BW==BW2)) / prod(size(BW))

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Leandro Hidalgo Torres
Leandro Hidalgo Torres on 25 Oct 2019
Hi,
Jaccard needs their arguments to be logical type. Check the data type of BW and BW2, surely they are uint8 type. If it's true, use BW=logical(BW) and the problem will be solved,
Best regards,
LH

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