1\ 2.\" This man page was generated by the Netpbm tool 'makeman' from HTML source. 3.\" Do not hand-hack it! If you have bug fixes or improvements, please find 4.\" the corresponding HTML page on the Netpbm website, generate a patch 5.\" against that, and send it to the Netpbm maintainer. 6.TH "Pbmclean User Manual" 0 "19 November 2011" "netpbm documentation" 7 8.SH NAME 9 10pbmclean - despeckle a PBM image 11 12.UN synopsis 13.SH SYNOPSIS 14 15\fBpbmclean\fP 16[\fB-minneighbors=\fP\fIN\fP] 17[\fB-black\fP|\fB-white\fP] 18[\fB-extended\fP] 19[\fIpbmfile\fP] 20 21.SH OPTION USAGE 22.PP 23You can use the minimum unique abbreviation of the options. You 24can use two hyphens instead of one. You can separate an option name 25from its value with white space instead of an equals sign. 26 27.UN description 28.SH DESCRIPTION 29.PP 30This program is part of 31.BR "Netpbm" (1)\c 32\&. 33.PP 34\fBpbmclean\fP cleans up a PBM image of random specks. It reads a 35PBM image as input and outputs a PBM that is the same as the input 36except with isolated pixels inverted. 37.PP 38You can use \fBpbmclean \fP to clean up "snow" on bitmap 39images. 40.PP 41There are two ways \fBpbmclean\fP can define "isolated" pixels: 42simple and extended. When you specify \fB-extended\fP, \fBpbmclean\fP 43uses extended; otherwise it uses basic. 44 45.UN basic 46.SS 47.PP 48In basic mode, \fBpbmclean\fP looks at each pixel individually, and any 49pixel that doesn't have at least a minimum number of pixels of the same color 50touching it is considered isolated and \fBpbmclean\fP erases it. 51.PP 52The \fB-minneighbors\fP option specifies the minimum number of neighboring 53pixels of the same color for a pixel \fInot\fP to be considered 54isolated. 55.PP 56For example, if \fB-minneighbors\fP is two and there are two contiguous 57black pixels in an otherwise white field, each of those pixels is isolated, 58so \fBpbmclean\fP erases them - turns both white. 59.PP 60The default minimum 1 pixel - \fBpbmclean\fP flips only completely 61isolated pixels. 62.PP 63(A \fB-minneighbors\fP value greater than 8 generates a completely 64inverted image (but use \fBpnminvert\fP to do that) -- or a 65completely white or completely black image with the \fB-black\fP or 66\fB-white\fP option). 67.PP 68\fBpbmclean\fP considers the area beyond the edges of the image to 69be white. (This matters when you consider pixels right on the edge of 70the image). 71.PP 72\fBpbmclean\fP does not distinguish between foreground and background; by 73default, it flips isolated pixels of either color. But you can 74specify \fB-black\fP or \fB-white\fP to have it flip only pixels of one 75color. 76 77.UN extended 78.SS 79.PP 80In extended mode, \fBpbmclean\fP erases all blobs which don't have the 81specified minimum number of pixels. A blob is a set of contiguous pixels of 82the foreground color. The minimum number of pixels is one plus 83the \fB-minneighbors\fP value. You specify the foreground color with 84\fB-black\fP and \fB-white\fP (default is black). 85.PP 86For example, if \fB-minneighbors\fP is 2 and the foreground color is 87black, and the image contains a straight line 4 pixels long, \fBpbmclean\fP 88erases that -- turns all four pixels white. \fBpbmclean\fP also erases 894 pixels in a square or L-shape. 90.PP 91The default \fB-minneighbors\fP is 4, so a blob must have at least 5 92pixels to escape \fBpbmclean\fP's purge. 93.PP 94Extended mode was new in Netpbm 10.56 (September 2011). 95 96 97.UN options 98.SH OPTIONS 99 100 101.TP 102\fB-black\fP 103 104.TP 105\fB-white\fP 106Flip pixels of the specified color. By default, if you specify 107neither \fB-black\fP nor \fB-white\fP, \fBpbmclean\fP flips both 108black and white pixels which do not have sufficient identical 109neighbors. If you specify \fB-black\fP, \fBpbmclean\fP leaves the 110white pixels alone and just erases isolated black pixels. Vice versa 111for \fB-white\fP. You may specify both \fB-black\fP and 112\fB-white\fP to get the same as the default behavior. 113 114.TP 115\fB-minneighbors=\fP\fIN\fP 116This determines how many pixels must be in a cluster in order 117for \fBpbmclean\fP to consider them legitimate and not clean them 118out of the image. See 119.UR #description 120Description 121.UE 122\&. 123.sp 124Before December 2001, \fBpbmclean\fP accepted \fB-\fP\fIN\fP 125instead of \fB-minneighbors\fP. Before Netpbm 10.27 (March 2005), 126\fB-minneighbors\fP was \fB-minneighbor\fP. 127 128.TP 129\fB-extended\fP 130\fBpbmclean\fP uses extended, as opposed to basic, isolated pixel 131detection. 132.sp 133This option was new in Netpbm 10.56 (September 2011). 134 135 136 137.UN seealso 138.SH SEE ALSO 139.BR "pbm" (5)\c 140\& 141 142.UN author 143.SH AUTHOR 144 145Copyright (C) 1990 by Angus Duggan 146Copyright (C) 1989 by Jef Poskanzer. 147Copyright (C) 2001 by Michael Sternberg. 148.PP 149Permission to use, copy, modify, and distribute this software and its 150documentation for any purpose and without fee is hereby granted, provided 151that the above copyright notice appear in all copies and that both that 152copyright notice and this permission notice appear in supporting 153documentation. This software is provided "as is" without express or 154implied warranty. 155.SH DOCUMENT SOURCE 156This manual page was generated by the Netpbm tool 'makeman' from HTML 157source. The master documentation is at 158.IP 159.B http://netpbm.sourceforge.net/doc/pbmclean.html 160.PP