Manual: pbmtopgm

Pbmtopgm User Manual(1)				   General Commands Manual			     Pbmtopgm User Manual(1)

NAME
       pbmtopgm - convert PBM image to PGM by averaging areas

SYNOPSIS
       pbmtopgm width height [pbmfile]

DESCRIPTION
       This program is part of Netpbm(1).

       pbmtopgm	 reads	a PBM image as input.  It outputs a PGM image in which each pixel's gray level is the average of the
       surrounding black and white input pixels.  The surrounding area is a rectangle of width by height pixels.

       In other words, this is a convolution.  pbmtopgm is similar to a special case of pnmconvol.

       You may need a pnmsmooth step after pbmtopgm.

       pbmtopgm has the effect of anti-aliasing bitmaps which contain distinct line features.

       pbmtopgm works best with odd sample width and heights.

       You don't need pbmtopgm just to use a PGM program on a PBM image.  Any PGM program (assuming it uses the	 Netpbm	 li‐
       braries	to read the PGM input) takes PBM input as if it were PGM, with only the minimum and maximum gray levels.  So
       unless your convolution rectangle is bigger than one pixel, you're not gaining anything with a pbmtopgm step.

       The opposite transformation (which would turn a PGM into a PBM) is dithering.  See pamditherbw.

OPTIONS
       There are no command line options defined specifically for pbmtopgm, but it recognizes the options common to all pro‐
       grams based on libnetpbm (See  Common Options .)

SEE ALSO
       pamditherbw(1), pnmconvol(1), pbm(1), pgm(1)

AUTHOR
       Copyright (C) 1990 by Angus Duggan.

       Copyright (C) 1989 by Jef Poskanzer.

       Permission to use, copy, modify, and distribute this software and its documentation for any purpose and	without	 fee
       is  hereby granted, provided that the above copyright notice appear in all copies and that both that copyright notice
       and this permission notice appear in supporting documentation.  This software is provided "as is" without express  or
       implied warranty.

DOCUMENT SOURCE
       This manual page was generated by the Netpbm tool 'makeman' from HTML source.  The master documentation is at

	      http://netpbm.sourceforge.net/doc/pbmtopgm.html

netpbm documentation					 05 Feb 2003				     Pbmtopgm User Manual(1)