pbmtopgm(1) [minix man page]
pbmtopgm(1) General Commands Manual pbmtopgm(1) NAME
pbmtopgm - convert portable bitmap to portable graymap by averaging areas SYNOPSIS
pbmtopgm width height [pbmfile] DESCRIPTION
pbmtopgm reads a portable bitmap as input. It outputs a portable graymap in which each pixel's gray level is the average the surrounding black and white input pixels. The surrounding area is a rectangle of width by height pixels. In other words, this is a convolution. pbmtopgm is similar to a special case of pnmconvol. You may need a ppmsmooth step after pbmtopgm. pbmtopgm has the effect of anti-aliasing bitmaps which contain distinct line features. pbmtopgm works best with odd sample width and heights. You don't need pbmtopgm just to use a PGM program on a PBM image. Any PGM program (assuming it uses the Netpbm libraries to read the PGM input) takes PBM input as if it were PGM, with only the mininum and maximum gray levels. So unless your convolution rectangle is bigger than one pixel, you're not gaining anything with a pbmtopgm step. SEE ALSO
netpbm(1), pgmtopbm(1), pbm(5) AUTHOR
Copyright (C) 1990 by Angus Duggan Copyright (C) 1989 by Jef Poskanzer. 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. 03 Sep 2001 pbmtopgm(1)
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pbmclean(1) General Commands Manual pbmclean(1) NAME
pbmclean - flip isolated pixels in portable bitmap SYNOPSIS
pbmclean [-minneighbors=N] [-black|-white] [pbmfile] 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. Before December 2001, pbmclean accepted -N instead of -minneighbors. DESCRIPTION
pbmclean cleans up a PBM image of random specs. It reads a PBM image as input and outputs a PBM that is the same as the input except with every pixel which has less than N identical neighbours inverted. The default for N is 1 - only completely isolated pixels are flipped. (A value of N greater than 8 generates a completely inverted image (but use pnminvert to do that) -- or a completely white or completely 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). You can use pbmclean to clean up "snow" on bitmap images. OPTIONS
-black -white Flip pixels of the specified color. By default, if you specify neither -black nor -white, pbmclean flips both black and white pix- els 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. SEE ALSO
pbm(5) 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. 18 Oct 2001 pbmclean(1)