MATLAB: How to find the boundaries of a value in a matrix

Question

Hi, I have a matrix as follows:

I =

     1     1     1     1     8     1     2
     1     1     8     8     8     2     1
     1     8     8     1     2     1     1
     1     1     8     2     1     1     1
     2     2     2     1     1     1     1
     2     2     2     1     1     1     1

I want a matrix which will be output of boundary value of 8 i.e. (1,5),(2,3),(2,4),(2.5),(3,2),(3.3),(4.3)

Is there any way to he find these location easily?

Answer 1

[r c] = find(bwperim(I==8));