.TH pnmcrop 1 "18 March 2001"
.IX pnmcrop
.SH NAME
pnmcrop - crop a portable anymap
.SH SYNOPSIS
.B pnmcrop
.RB [ -white | -black | -sides ]
.RB [ -left ]
.RB [ -right ]
.RB [ -top ]
.RB [ -bottom ]
.RI [ pnmfile ]

All options may be abbreviated to their shortest unique prefix or
specified with double hyphens.

.SH DESCRIPTION
Reads a PBM, PGM, or PPM image as input.  Removes borders that are the
background color, and produces the same type of image as output.
.IX cropping

If you don't specify otherwise,
.B pnmcrop
assumes the background color is whatever color the top left and right
corners of the image are and if they are different colors, something
midway between them.  You can specify that the background is white or
black with the
.B -white
and 
.B -black
options or make
.B pnmcrop
base its guess on all four corners instead of just two with 
.BR -sides .

By default, 
.B pnmcrop
chops off any stripe of background color it finds, on all four sides.
You can tell
.B pnmcrop
to remove only specific borders with the
.BR -left ,
.BR -right ,
.BR -top ,
and
.BR -bottom 
options.

If you want to chop a specific amount off the side of an image, use
.BR pnmcut .

If you want to add different borders after removing the existing ones,
use
.BR pnmcat
or 
.BR pnmcomp .

.SH OPTIONS
.PP
.TP
.B -white
Take white to be the background color.  
.B pnmcrop 
removes borders which are white.
.TP 
.B -black
Take black to be the background color.  
.B pnmcrop 
removes borders which are black.
.TP
.B -sides
Determine the background color from the colors of the four corners of 
the input image.  
.B pnmcrop
removes borders which are of the background color.

If at least three of the four corners are the same color, 
.B pnmcrop 
takes that as the background color.
If not, 
.B pnmcrop
looks for two corners of the same color in the following order, taking
the first found as the background color: top, left, right, bottom.  If
all four corners are different colors,
.B pnmcrop
assumes an average of the four colors as the background color.

The 
.B -sides
option slows 
.B pnmcrop
down, as it reads the entire image to determine the background color
in addition to the up to three times that it would read it without
.BR -sides .

.TP
.B -left
Remove any left border.
.TP
.B -right
Remove any right border.
.TP
.B -top
Remove any top border.
.TP
.B -bottom
Remove any bottom border.
.TP
.B -verbose
Print on Standard Error information about the processing, including
exactly how much is being cropped off of which sides.


.SH "SEE ALSO"
.BR pnmcut (1), 
.BR pnmfile (1),
.BR pnm (5)

.SH AUTHOR
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.