The Laplace edge detection method uses a $3$x$3$ template for each image pixel:

$1.$ Multiply each original pixel by $4$ and subtract the $4$ neighboring pixels, ignoring a one$-$pixel$-$wide border around the image.

$2.$ Each absolute numeric edge value greater than a threshold is an edge $(1),$ all others are not $(0).$ All borders are no edges $(0).$