How do I fill 4-connected cells in an matrix?

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Julia
Julia 2011-3-30
I have a problem. I would like to convert a matrix like this:
A=[ 1 1 1 0 1 0; 1 0 1 1 0 1; 1 1 1 0 1 0; 0 0 0 0 0 0]
to
B=[1 1 1 0 1 0; 1 1 1 1 1 1 ; 1 1 1 0 1 0; 0 0 0 0 0 0]
that is fill 4-connected cells containing 0 with 1. I have tried to use imfill but I think it is not useful in this specific case.

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回答（3 个）

Steve Eddins
Steve Eddins 2011-3-30
>> imfill(A,4,'holes')
ans =
1 1 1 0 1 0
1 1 1 1 1 1
1 1 1 0 1 0
0 0 0 0 0 0
  1 个评论
Julia
Julia 2011-3-31
Hi,
thank you for the answers but this option does not give exactly what I need. The example matrix was probably not a good one. I show another example. If:
BW1 = logical([1 0 0 0 0 0 0 0
1 1 1 1 1 0 0 0
1 0 0 0 1 0 1 0
1 0 0 0 1 1 1 0
1 1 1 1 0 1 1 1
1 0 0 1 1 0 1 0
1 0 0 0 1 0 1 0
1 0 0 0 1 1 1 0]);
with the command:
BW2 = imfill(BW1,4,'holes');
you get:
BW2 =
1 0 0 0 0 0 0 0
1 1 1 1 1 0 0 0
1 1 1 1 1 0 1 0
1 1 1 1 1 1 1 0
1 1 1 1 1 1 1 1
1 0 0 1 1 1 1 0
1 0 0 0 1 1 1 0
1 0 0 0 1 1 1 0
but I would like to fill only the cells with 0 which are 4-connected with 1s, that is, I would like to get the following matrix instead:
BW3 =
1 0 0 0 0 0 0 0
1 1 1 1 1 0 0 0
1 0 0 0 1 0 1 0
1 0 0 0 1 1 1 0
1 1 1 1 1 1 1 1
1 0 0 1 1 0 1 0
1 0 0 0 1 0 1 0
1 0 0 0 1 1 1 0
Do you know if there is still an easy way to get this?
Again, thank you in advance.

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Anathea Pepperl
Anathea Pepperl 2011-3-30
If you have the Image Processing Toolbox, then imfill should work in this case. I tried replicating your code here:
A = [ 1 1 1 0 1 0; 1 0 1 1 0 1; 1 1 1 0 1 0; 0 0 0 0 0 0]
B = [1 1 1 0 1 0; 1 1 1 1 1 1 ; 1 1 1 0 1 0; 0 0 0 0 0 0]
C = imfill(A, 'holes')
isequal(C, B)
And using imfill to generate the matrix C gave me the same result as B.
  1 个评论
Julia
Julia 2011-3-31
Hi,
thank you for the answers but this option does not give exactly what I need. The example matrix was probably not a good one. I show another example. If:
BW1 = logical([1 0 0 0 0 0 0 0
1 1 1 1 1 0 0 0
1 0 0 0 1 0 1 0
1 0 0 0 1 1 1 0
1 1 1 1 0 1 1 1
1 0 0 1 1 0 1 0
1 0 0 0 1 0 1 0
1 0 0 0 1 1 1 0]);
with the command:
BW2 = imfill(BW1,4,'holes');
you get:
BW2 =
1 0 0 0 0 0 0 0
1 1 1 1 1 0 0 0
1 1 1 1 1 0 1 0
1 1 1 1 1 1 1 0
1 1 1 1 1 1 1 1
1 0 0 1 1 1 1 0
1 0 0 0 1 1 1 0
1 0 0 0 1 1 1 0
but I would like to fill only the cells with 0 which are 4-connected with 1s, that is, I would like to get the following matrix instead:
BW3 =
1 0 0 0 0 0 0 0
1 1 1 1 1 0 0 0
1 0 0 0 1 0 1 0
1 0 0 0 1 1 1 0
1 1 1 1 1 1 1 1
1 0 0 1 1 0 1 0
1 0 0 0 1 0 1 0
1 0 0 0 1 1 1 0
Do you know if there is still an easy way to get this?
Again, thank you in advance.

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Steve Eddins
Steve Eddins 2011-3-31
I posted an answer (using bwhitmiss) in response to your new question.

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