MATLAB: After if condition the value is not assigning, the default value 255 is coming

Image Processing Toolboxseeded region alg

% seeded region growing algorithm %

clear all; clc;

 I = imread('7.jpg');
 Is = imresize(I,[256 256]);
 Ig = rgb2gray(Is);
 impixelinfo(imshow(Ig));
 % determine how many clusters for an image %

c1 = 300; c2 = 500; c3 = 600;

 %determine how many seed points u reqire%
 p1 = 228;
 p2 = 198;
 p3 = 100;
 %difference of pixel values of seed point to neighbouring pixels%
 for i =1:256
     for j =1:256
         if abs(p1 - Ig(i,j)) <= 5
               Ig(i,j) = 300;
         elseif abs(p2 -Ig(i,j)) <= 5
                   Ig(i,j) = 600;
         else
             Ig(i,j) = 700;
         end
     end
 end

Best Answer

This is not seed growing - nothing is growing. You are quantizing, which you can do like this without a loop

outputImage = 700 * ones(256,256, 'uint32'); % Initialize to all 700.
binaryImage = Ig >= (p1-5) & Ig <= (p1+5);
outputImage(binaryImage) = 300;
binaryImage = Ig >= (p2-5) & Ig <= (p2+5);
outputImage(binaryImage) = 600;

I have no idea where 255 is coming from - you don't even have a 255 in your code at all!

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You have

    for j=1:n
      a11=Ix(i,j)./sqrt(Ig(i,j).^2.*(1+mu.^2.*Ig(i,j).^2));
      a12=-Iy(i,j)./Ig(i,j);
      a13=-mu.*Ix(i,j)./sqrt(1+mu.^2.*Ig(i,j).^2);
      a21=Iy(i,j)./sqrt(Ig(i,j).^2.*(1+mu.^2.*Ig(i,j).^2));
      a22=Ix(i,j)./Ig(i,j);
      a23=-mu.*Iy(i,j)./sqrt(1+mu.^2.*Ig(i,j).^2);
      a31=mu.*Ig(i,j).^2./sqrt(Ig(i,j).^2.*(1+mu.^2.*Ig(i,j).^2));
      a32=0;
      a33=1./sqrt(1+mu.^2.*Ig(i,j).^2);
  end

every iteration of that overwrites all of the variables. You should not bother to do the iterations before j = n, or you should save all of the outputs, such as

for j=1:n
    a11(j)=Ix(i,j)./sqrt(Ig(i,j).^2.*(1+mu.^2.*Ig(i,j).^2));
    a12(j)=-Iy(i,j)./Ig(i,j);
    a13(j)=-mu.*Ix(i,j)./sqrt(1+mu.^2.*Ig(i,j).^2);
    a21(j)=Iy(i,j)./sqrt(Ig(i,j).^2.*(1+mu.^2.*Ig(i,j).^2));
    a22(j)=Ix(i,j)./Ig(i,j);
    a23(j)=-mu.*Iy(i,j)./sqrt(1+mu.^2.*Ig(i,j).^2);
    a31(j)=mu.*Ig(i,j).^2./sqrt(Ig(i,j).^2.*(1+mu.^2.*Ig(i,j).^2));
    a32(j)=0;
    a33(j)=1./sqrt(1+mu.^2.*Ig(i,j).^2);
end

Now when you reach

    P=[a11 a12 a13; a21 a22 a23; a31 a32 a33];

you have to decide how you want those vectors to go together. Perhaps you want

    P=[a11(:) a12(:) a13(:); a21(:) a22(:) a23(:); a31(:) a32(:) a33(:)];

After that you face the problem that you want to save that P for every i. That could lead to

    P{i}=[a11(:) a12(:) a13(:); a21(:) a22(:) a23(:); a31(:) a32(:) a33(:)];

However... my suspicion is that what you want is really,

n = size(Image, 1);
m = size(Image, 2);
P = cell(n, m);
for i=1:n
  for j=1:m
      a11=Ix(i,j)./sqrt(Ig(i,j).^2.*(1+mu.^2.*Ig(i,j).^2));
      a12=-Iy(i,j)./Ig(i,j);
      a13=-mu.*Ix(i,j)./sqrt(1+mu.^2.*Ig(i,j).^2);
      a21=Iy(i,j)./sqrt(Ig(i,j).^2.*(1+mu.^2.*Ig(i,j).^2));
      a22=Ix(i,j)./Ig(i,j);
      a23=-mu.*Iy(i,j)./sqrt(1+mu.^2.*Ig(i,j).^2);
      a31=mu.*Ig(i,j).^2./sqrt(Ig(i,j).^2.*(1+mu.^2.*Ig(i,j).^2));
      a32=0;
      a33=1./sqrt(1+mu.^2.*Ig(i,j).^2);
      P{n, m}=[a11 a12 a13; a21 a22 a23; a31 a32 a33];
  end
end

Best Answer

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