otsu's code

I need code to segment red area only from this image

[KALYAN ACHARJYA]

Otsu code use for Global Thresholding.

[T SM]=graythresh(input gray image);

Where T=Threshold>output from following code function otsuthresh SM=Separability Measure

Source: Gonzalez Book (Image Processing+Matlab)

Answer 1

[KALYAN ACHARJYA]

%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

Answer 2

[Image Analyst]

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;