pbmclean man page on Pidora

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Pbmclean User Manual(0)				       Pbmclean User Manual(0)

NAME
       pbmclean - despeckle a PBM image

SYNOPSIS
       pbmclean [-minneighbors=N] [-black|-white] [-extended] [pbmfile]

OPTION USAGE
       You  can	 use  the minimum unique abbreviation of the options.  You can
       use two hyphens instead of one.	You can separate an option  name  from
       its value with white space instead of an equals sign.

DESCRIPTION
       This program is part of Netpbm(1).

       pbmclean	 cleans up a PBM image of random specks.  It reads a PBM image
       as input and outputs a PBM that is the same as the  input  except  with
       isolated pixels inverted.

       You can use pbmclean  to clean up 'snow' on bitmap images.

       There  are  two	ways pbmclean can define 'isolated' pixels: simple and
       extended.  When you specify -extended, pbmclean uses  basic;  otherwise
       it uses extended.

       In basic mode, pbmclean looks at each pixel individually, and any
       pixel that doesn't have at least a minimum number of pixels of the same
       color touching it is considered isolated.  E.g. if the minimum  is  two
       and  there are two contiguous black pixels in an otherwise white field,
       each of those pixel is isolated.

       The -minneighbors option specifies the minimum  number  of  neighboring
       pixels of the same color for a pixel not to be considered isolated.

       The default is 1 pixel -- only completely isolated pixels are flipped.

       (A  -minneighbors  value greater than 8 generates a completely inverted
       image (but use pnminvert to do that) -- or a completely white  or  com‐
       pletely black image with the -black or -white option).

       pbmclean	 considers the area beyond the edges of the image to be white.
       (This matters when you consider pixels right on the edge of the image).

       pbmclean does not distinguish between  foreground  and  background;  by
       default, it flips isolated pixels of either color.  But you can specify
       -black or -white to have it flip only pixels of one color.

       In extended mode, pbmclean erases all blobs which don't have the
       specified minimum number of pixels.  A blob is a set of contiguous pix‐
       els  of the foreground color.  The minimum number of pixels is one plus
       the -minneighbors value.	 You specify the foreground color with	-black
       and -white (default is black).

       For  example,  if  minneighbors is 2 and the foreground color is black,
       and the image contains a straight line 4 pixels long,  pbmclean	erases
       that  -- turns all four pixels white.  pbmclean also erases 4 pixels in
       a square or L-shape.

       The default -minneighbors is 4, so a blob must have at least  5	pixels
       to escape pbmclean's purge.

       Extended mode was new in Netpbm 10.56 (September 2011).

OPTIONS
       -black

       -white Flip  pixels of the specified color.  By default, if you specify
	      neither -black nor -white, pbmclean flips both black  and	 white
	      pixels which do not have sufficient identical neighbors.	If you
	      specify -black, pbmclean leaves the white pixels alone and  just
	      erases  isolated	black pixels.  Vice versa for -white.  You may
	      specify both -black and -white to get the same  as  the  default
	      behavior.

       -minneighbors=N
	      This  determines	how  many pixels must be in a cluster in order
	      for pbmclean to consider them legitimate and not clean them  out
	      of the image.  See Description ⟨#description⟩ .

	      Before December 2001, pbmclean accepted -N instead of -minneigh‐
	      bors.  Before Netpbm 10.27 (March 2005), -minneighbors was -min‐
	      neighbor.

       -extended
	      pbmclean	uses  extended,	 as  opposed  to basic, isolated pixel
	      detection.

	      This option was new in Netpbm 10.56 (September 2011).

SEE ALSO
       pbm(1)

AUTHOR
       Copyright (C) 1990 by Angus Duggan Copyright (C) 1989 by Jef Poskanzer.
       Copyright (C) 2001 by Michael Sternberg.

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

netpbm documentation		28 August 2011	       Pbmclean User Manual(0)
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