MATLAB: Making matrix like in Wavefront algorithm

Question

I have this kind of matrix (13 x 13):

0   0   0   0   0   0   0   0   0   0   0   0   0
0   1   1   1   1   1   1   1   1   1   1   1   0
0   1   1   1   1   1   1   1   1   1   1   1   0
0   1   1   1   1   1   1   1   1   1   1   1   0
0   1   1   1   1   1   1   1   1   1   1   1   0
0   1   1   1   1   1   1   1   1   1   1   1   0
0   1   1   1   1   1   0   1   1   1   1   1   0
0   1   1   1   1   1   1   1   1   1   1   1   0
0   1   1   1   1   1   1   1   1   1   1   1   0
0   1   1   1   1   1   1   1   1   1   1   1   0
0   1   1   1   1   1   1   1   1   1   1   1   0
0   1   1   1   1   1   1   1   1   1   1   1   0
0   0   0   0   0   0   0   0   0   0   0   0   0

Can I somehow increase the values around the central zero and the zeros that make the "walls" by one at each iteration and make it as this?

0   0   0   0   0   0   0   0   0   0   0   0   0
0   1   1   1   1   1   1   1   1   1   1   1   0
0   1   2   2   2   2   2   2   2   2   2   1   0
0   1   2   3   3   3   3   3   3   3   2   1   0
0   1   2   3   2   2   2   2   2   3   2   1   0
0   1   2   3   2   1   1   1   2   3   2   1   0
0   1   2   3   2   1   0   1   2   3   2   1   0
0   1   2   3   2   1   1   1   2   3   2   1   0
0   1   2   3   2   2   2   2   2   3   2   1   0
0   1   2   3   3   3   3   3   3   3   2   1   0
0   1   2   2   2   2   2   2   2   2   2   1   0
0   1   1   1   1   1   1   1   1   1   1   1   0
0   0   0   0   0   0   0   0   0   0   0   0   0

Answer 1

If you have the image processing toolbox, it's a one-liner:

%# assume your matrix is called A
result = bwdist(~A,'cityblock')

'result' is the distance of each non-zero pixel in A to the nearest zero if you can only step horizontally or vertically.