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Revision: 69518
at July 7, 2015 07:00 by engrhassan2k13
Initial Code 
%read image
img1 = rgb2gray(imread('dino.jpg'));%use your image here
imshow(img1);

%parameter initialization for EM-Algo
temp =[];
phi1 = 0.5;
phi2 = 0.5;
u1  = 0;
u2 = 50;
sig1 = 2;
sig2 = 3;
tempimg1 = reshape(img1,1,numel(img1));
tempimg1 = double(tempimg1);
img = double (img1);


for k = 1 : 3

for i = 1 : numel(img1)
       %Expectation Step 
       prob1 =  -0.9181-reallog(sig1)-(  (( img(i)- u1 )^2)/(2*(sig1^2))  );
       prob2 =  -0.9181-reallog(sig2)-(  (( img(i)- u2 )^2)/(2*(sig2^2))  );
       
       probc1 = ( prob1*phi1 ) / ( (prob1*phi1)+ (prob2*phi2) );
       probc2 = ( prob2*phi2 )/( (prob1*phi1) + (prob2*phi2) );
       
       temp = [temp ; probc1 probc2];
    
end
       %Maximization Step

       phi1 = ( sum(temp(:,1)) )*(1/numel(img));
       phi2 = (sum(temp(:,2)))*(1/numel(img));
      
       
       u1 = ( sum((temp(:,1)').*tempimg1) )/( sum(temp(:,1)) );
       u2 = ( sum((temp(:,2)').*tempimg1) )/( sum(temp(:,2)) );
       
       var1 =   ( sum( ( (tempimg1 - u1).^2  ).*( temp(:,1)' ) ) ) / ( sum(temp(:,1)) ); 
       sig1 = sqrt(var1);
       var2 =   ( sum( ( (tempimg1 - u2).^2  ).*( temp(:,2)' ) ) ) / ( sum(temp(:,2)) );
       sig2 = sqrt(var2);
       
       temp = [];
       
end
       
%Thresholding
thresh = ((u2 + u1)/2);

for m = 1 : numel(img1)
    if img1(m) > thresh
        img1(m) = 255;
    else
        img1(m) = 0;
    end
end

figure;
imshow(img1);
Initial URL 

                                

                                                            

                                    

                                        

                                        Initial Description
                                        

                                    

                                    
This code uses the Expectation Maximization algorithm for automatically thresholding an image.

                                

                                                            

                                    

                                        

                                        Initial Title
                                        

                                    

                                    
Automatic Thresholding with Expectation Maximization Algorithm in Matlab

                                

                                                            

                                    

                                        

                                        Initial Tags
                                        

                                    

                                    

                                

                                                            

                                    

                                        

                                        Initial Language
                                        

                                    

                                    
MatLab