easter egg :)
if you use the following pattern:
[
[0.5, 0.5, 0.5],
[0.5, -5, 0.5],
[0.5, 0.5, 0.5],
]
and make sure that instead of red, you place black, it would give you the outline of the image.
if you use the following one:
[
[1, 1, 1],
[0, 0, 0],
[-1, -1, -1],
]
this would give you a vertical edge detection instead of a horizontal one.