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sheno39
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how to make zero padding?

Asked by sheno39
on 8 Oct 2013
Latest activity Commented on by Image Analyst
on 5 Apr 2016
can anyone help me to make zero padding for a 4x3 matrix. i have to add a row of zeros in the top,bottom, left and right side of the matrix

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8 Answers

Image Analyst
Answer by Image Analyst
on 8 Oct 2013
 Accepted Answer

If you have the Image Processing Toolbox, you can use padarray().

  2 Comments

sheno39
on 8 Oct 2013
Thank You Sir.
Jie
on 9 Oct 2013
cool

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Answer by Slim Ben Ghalba on 21 Nov 2013

a smarter and simpler way. here is an example for zero-padding with 4:
>> a=zeros(1,12)
a =
0 0 0 0 0 0 0 0 0 0 0 0
>> a(1:4:end)=1
a =
1 0 0 0 1 0 0 0 1 0 0 0

  1 Comment

Image Analyst
on 15 Jul 2014
This does not wrap the matrix with a layer of zeros on all sides like the original poster asked or like padarray() does.

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cr
Answer by cr
on 8 Oct 2013
Edited by cr
on 8 Oct 2013

m = [zeros(1,size(m,2)+2); [zeros(size(m,1),1), m, zeros(size(m,1),1)]; zeros(1,size(m,2)+2)];
or even simpler, but needs creating a temp variable:
tmp = zeros(size(m)+2);
tmp(2:end-1,2:end-1) = m;
m = tmp;
Cheers.

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Jie
Answer by Jie
on 8 Oct 2013
Edited by Jie
on 8 Oct 2013

function out_put =adpadding(in_put)
% just wish you matrix size is not too large
[n m]=size(in_put);
A=['a' 'b' 'c' 'd' 'e' 'f' 'g' 'h' 'i' 'j' 'k' 'l' 'm' 'n' 'o' ];
B=1:20;
xlswrite('addapaddle.xls',0,'sheet1','a1');
str1=[A(m+2), num2str(B(n+2))];
xlswrite('addapaddle.xls',0,'sheet1',str1);
str2=['b2:' A(m+1), num2str(B(n+1))];
xlswrite('addapaddle.xls',in_put,'sheet1',str2);
str3=['a1:' str1];
out_put=xlsread('addapaddle.xls','sheet1',str3);
out_put(isnan(out_put))=0;
delete('addapaddle.xls')
could take some time, but save much effort regarding the mat size. I think the string part could be optimized somehow, but i just don't know how. Also u can try some simple but boring methods. like
a(1,2:end-1)=ones(1,size(a,2)-1)
or the alike.

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Jos (10584)
Answer by Jos (10584)
on 8 Oct 2013
Edited by Jos (10584)
on 8 Oct 2013

Pad a matrix M with N zeros to all sides using indexing (neither trivial nor boring):
M = ceil(10*rand(3,4))
N = 2
if N > 0
M(end+2*N,end+2*N) = 0
M = M([end-N+1:end 1:end-N], [end-N+1:end 1:end-N])
end
If you have the image toolbox, take a look at PADARRAY.

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Answer by FRANCISCO JAVIER on 8 Oct 2013

M=rand(2,1);
K=[zeros(2,1) M zeros(2,1)];
N=[zeros(1,3); K; zeros(1,3)];

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Answer by Kiarash Ahi on 15 Jul 2014
Edited by Kiarash Ahi on 15 Jul 2014

Try this as well:
function kp=padding(k)
[M N]=size(k);
for n=1:2:N
k(:,n)=0
end
end

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Answer by Md. Kamal Hossain on 5 Apr 2016

How to add zero in a sequence

  1 Comment

Image Analyst
on 5 Apr 2016
If the sequence is stored in a vector, and index is the location where you want to add/insert the zeros:
newVec = [vec(1:index-1), 0, vec(index:end)];

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