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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