[atum47]

Yeah, I was thinking about writing a blog post about it but I did not know if people would be interested.

For the filter try this

     0 -1  0
    -1  5 -1
     0 -1  0

This will apply a sharp filter to a loaded image

    0  1  0
    1 -3  1
    0  1  0

This one will bluer the image