# info > ppmrelief

[ppmrelief(1)](https://www.chedong.com/phpMan.php/man/ppmrelief/1/markdown)                General Commands Manual               [ppmrelief(1)](https://www.chedong.com/phpMan.php/man/ppmrelief/1/markdown)

## NAME
       ppmrelief - run a Laplacian relief filter on a portable pixmap

## SYNOPSIS
       ppmrelief [ppmfile]

## DESCRIPTION
       Reads  a portable pixmap as input.  Does a Laplacian relief filter, and
       writes a portable pixmap as output.

       The Laplacian relief filter is described  in  "Beyond  Photography"  by
       Holzmann, equation 3.19.  It's a sort of edge-detection.

## SEE ALSO
       [pgmbentley(1)](https://www.chedong.com/phpMan.php/man/pgmbentley/1/markdown), [pgmoil(1)](https://www.chedong.com/phpMan.php/man/pgmoil/1/markdown), [ppm(5)](https://www.chedong.com/phpMan.php/man/ppm/5/markdown)

## AUTHOR
       Copyright (C) 1990 by Wilson Bent (<whb@hoh-2.att.com>)

                                11 January 1991                   [ppmrelief(1)](https://www.chedong.com/phpMan.php/man/ppmrelief/1/markdown)