pnmcrop - crop a portable anymap
SYNOPSIS
pnmcrop [-white|-black|-sides] [-left] [-right] [-top]
[-bottom] [pnmfile]
All options may be abbreviated to their shortest unique
prefix or specified with double hyphens.
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.
If you don't specify otherwise, pnmcrop assumes the back
ground color is whatever color the top left and right cor
ners 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 -white and -black
options or make pnmcrop base its guess on all four corners
instead of just two with -sides.
By default, pnmcrop chops off any stripe of background
color it finds, on all four sides. You can tell pnmcrop
to remove only specific borders with the -left, -right,
-top, and -bottom options.
If you want to chop a specific amount off the side of an
image, use pnmcut.
If you want to add different borders after removing the
existing ones, use pnmcat or pnmcomp.
OPTIONS
-white Take white to be the background color. pnmcrop
removes borders which are white.
-black Take black to be the background color. pnmcrop
removes borders which are black.
-sides Determine the background color from the colors of
the four corners of the input image. pnmcrop
removes borders which are of the background color.
If at least three of the four corners are the same
color, pnmcrop takes that as the background color.
If not, 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,
pnmcrop assumes an average of the four colors as
The -sides option slows 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 -sides.
-left Remove any left border.
-right Remove any right border.
-top Remove any top border.
-bottom
Remove any bottom border.
-verbose
Print on Standard Error information about the pro
cessing, including exactly how much is being
cropped off of which sides.
SEE ALSO
pnmcut(1), pnmfile(1), pnm(5)
AUTHOR
Copyright (C) 1989 by Jef Poskanzer.
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