Image Toolbox Conceptual Problem

Hello,

I am working on a project for a friend using image toolbox. I have to demonstrate how to build an "arbitrary" coefficient filter with the following constraints.

1. The filter kernel is 3x3 2. Maximum image size is 32x32 3. Assume that the border pad is done via pixel mirroring of the image.

I know it has to be 5 bits but other than that i'm not sure how to get started.

Thanks