Interpolation question

[rkj(at)dukebar.crml.uab.edu (R. Kyle Justice)]

I have an image containg some bad values.  I would like
to replace these points with the average value of their
neighbors.  Is there an easy way to do this without loops?

For instance, a 3x3 array as follows:

1 1 1
1 0 1
1 1 1

would become

1 1 1
1 1 1
1 1 1.

I can't get the boundary conditions to work correctly when
I use CONVOL.  It either zeros the edges or does not process 
them.

For instance,

1 1 1
0 1 1
1 1 0

should be 

1 1 1
1 1 1
1 1 1

as well.


Kyle J.