how to make zero padding?

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

Answer 1

[Image Analyst]

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

[sheno39]

Thank You Sir.

[Jie]

cool

Answer 2

[cr]

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.

Answer 3

[Jos (10584)]

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.

Answer 4

[Slim Ben Ghalba]

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

[Image Analyst]

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

Answer 5

[Jie]

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.

Answer 6

[FRANCISCO JAVIER]

M=rand(2,1);

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

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

Answer 7

[Kiarash Ahi]

Try this as well:

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

Answer 8

[Md. Kamal Hossain]

How to add zero in a sequence

[Image Analyst]

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)];