getborder

returns a logical border inside or outside a mask

Ib = getborder(I,method)

getborder returns the outline around logical values in I (mask) using a 8-connected neighborhood.
I must be a logical n*m matrix. method 'inside' returns the inner border around "islands" of logical values. 'outside' returns the border outside the islands.

Example:

I = peaks(8)<0;

Ib = getborder(I,'inside')

Ib =

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

Ib = getborder(I,'outside')

Ib =

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