1Pbmclean User Manual(0) Pbmclean User Manual(0)
2
6 pbmclean - despeckle a PBM image
7
10 pbmclean [-minneighbors=N] [-black|-white] [-extended] [pbmfile]
11
14 You can use the minimum unique abbreviation of the options. You can
15 use two hyphens instead of one. You can separate an option name from
16 its value with white space instead of an equals sign.
17
20 This program is part of Netpbm(1).
21 pbmclean cleans up a PBM image of random specks. It reads a PBM image
23 as input and outputs a PBM that is the same as the input except with
24 isolated pixels inverted.
25 You can use pbmclean to clean up "snow" on bitmap images.
27 There are two ways pbmclean can define "isolated" pixels: simple and
29 extended. When you specify -extended, pbmclean uses extended; other‐
30 wise it uses basic.
31 Basic Mode
34 In basic mode, pbmclean looks at each pixel individually, and any pixel
35 that doesn't have at least a minimum number of pixels of the same color
36 touching it is considered isolated and pbmclean erases it.
37 The -minneighbors option specifies the minimum number of neighboring
39 pixels of the same color for a pixel not to be considered isolated.
40 For example, if -minneighbors is two and there are two contiguous black
42 pixels in an otherwise white field, each of those pixels is isolated,
43 so pbmclean erases them - turns both white.
44 The default minimum 1 pixel - pbmclean flips only completely isolated
46 pixels.
47 (A -minneighbors value greater than 8 generates a completely inverted
49 image (but use pnminvert to do that) -- or a completely white or com‐
50 pletely black image with the -black or -white option).
51 pbmclean considers the area beyond the edges of the image to be white.
53 (This matters when you consider pixels right on the edge of the image).
54 pbmclean does not distinguish between foreground and background; by
56 default, it flips isolated pixels of either color. But you can specify
57 -black or -white to have it flip only pixels of one color.
58 Extended Mode
61 In extended mode, pbmclean erases all blobs which don't have the speci‐
62 fied minimum number of pixels. A blob is a set of contiguous pixels of
63 the foreground color. The minimum number of pixels is one plus the
64 -minneighbors value. You specify the foreground color with -black and
65 -white (default is black).
66 For example, if -minneighbors is 2 and the foreground color is black,
68 and the image contains a straight line 4 pixels long, pbmclean erases
69 that -- turns all four pixels white. pbmclean also erases 4 pixels in
70 a square or L-shape.
71 The default -minneighbors is 4, so a blob must have at least 5 pixels
73 to escape pbmclean's purge.
74 Extended mode was new in Netpbm 10.56 (September 2011).
76
80 In addition to the options common to all programs based on libnetpbm
81 (most notably -quiet, see
82 Common Options ⟨index.html#commonoptions⟩ ), pbmclean recognizes the
83 following command line options:
84 -black
88 -white Flip pixels of the specified color. By default, if you specify
91 neither -black nor -white, pbmclean flips both black and white
92 pixels which do not have sufficient identical neighbors. If you
93 specify -black, pbmclean leaves the white pixels alone and just
94 erases isolated black pixels. Vice versa for -white. You may
95 specify both -black and -white to get the same as the default
96 behavior.
97 -minneighbors=N
100 This determines how many pixels must be in a cluster in order
101 for pbmclean to consider them legitimate and not clean them out
102 of the image. See Description ⟨#description⟩ .
103 Before December 2001, pbmclean accepted -N instead of -minneigh‐
105 bors. Before Netpbm 10.27 (March 2005), -minneighbors was -min‐
106 neighbor.
107 -extended
110 pbmclean uses extended, as opposed to basic, isolated pixel
111 detection.
112 This option was new in Netpbm 10.56 (September 2011).
114
119 pbm(1)
120
123 Copyright (C) 1990 by Angus Duggan Copyright (C) 1989 by Jef Poskanzer.
124 Copyright (C) 2001 by Michael Sternberg.
125 Permission to use, copy, modify, and distribute this software and its
127 documentation for any purpose and without fee is hereby granted, pro‐
128 vided that the above copyright notice appear in all copies and that
129 both that copyright notice and this permission notice appear in sup‐
130 porting documentation. This software is provided "as is" without
131 express or implied warranty.
132
134 This manual page was generated by the Netpbm tool 'makeman' from HTML
135 source. The master documentation is at
136 http://netpbm.sourceforge.net/doc/pbmclean.html
138netpbm documentation 19 November 2011 Pbmclean User Manual(0)