ppmrelief - run a Laplacian relief filter on a PPM image
This program is part of Netpbm(1).
ppmrelief reads a PPM image as input, does a Laplacian relief filter, and writes a PPM image as output.
The Laplacian relief filter is described in 'Beyond Photography' by Holzmann, equation 3.19. It's a sort of edge-detection.
Copyright (C) 1990 by Wilson Bent (firstname.lastname@example.org)