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otsu's code
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I need code to segment red area only from this image
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KALYAN ACHARJYA
on 29 Aug 2017
Edited: KALYAN ACHARJYA
on 29 Aug 2017
Otsu code use for Global Thresholding.
[T SM]=graythresh(input gray image);
Where T=Threshold>output from following code function otsuthresh SM=Separability Measure
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/186660/image.png)
Source: Gonzalez Book (Image Processing+Matlab)
Answers (2)
KALYAN ACHARJYA
on 29 Aug 2017
%if true
function [T,SM]=otsuthresh(h);
h=h/sum(h);
h=h(:);
i=(1:numel(h))';
P1=cumsum(h);
m=cumsum(i.*h);
mG=m(end);
sigSquared=((mG*P1-m).^2)./(P1.*(1-P1)+eps);
maxSigsq=max(sigSquared);
T=mean(find(sigSquared==maxSigsq));
T=(T-1)/(numel(h)-1);
SM=maxSigsq/(sum(((i-mG).^2).*h)+eps);
% end
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Image Analyst
on 29 Aug 2017
shaimaa, you would NOT use Otsu for that. You need to do it "manually". First identify the values of the starting and ending thermal values in your image. Let's say the red range starts at 32 degrees and ends at 33 degrees. So then to segment out those temperatures, you'd do
binaryImage = themalImage > 32 & thermalImage < 33;
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