MATLAB: How to do median filter without using medfilt2..

functionhomeworkmedian filter

hello, i need to do an image enhancement using median filter… but im not suppose to use medfilt2 or those function in matlab… how create my own function… im not sure on how to do it… can some1 help me in this..?? ~THANK YOU~

Best Answer

Use blockproc() or nlfilter() and inside the function call the sort() routine and take the middle value. If you can't even use those functions, then you'll have to do the whole thing yourself with a bunch of nested for loops.

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MATLAB: Having problem with error “index out of bounds” numel (Y)=1″

You're going overall rows and all columns but trying to access a 3x3 window around it. What will happen if you are at the edge of an image? You'd have i or j = -1. There is no -1 row. Try going from i = 1:rows, and j = 2:columns.

MATLAB: How to prevent output being overwritten in for loop

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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MATLAB: Having problem with error “index out of bounds” numel (Y)=1″

MATLAB: How to prevent output being overwritten in for loop

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