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Annotated edit history of pbmtopgm(1) version 1, including all changes. View license author blame.
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1 perry 1 pbmtopgm
2 !!!pbmtopgm
3 NAME
4 SYNOPSIS
5 DESCRIPTION
6 SEE ALSO
7 AUTHOR
8 ----
9 !!NAME
10
11
12 pbmtopgm - convert PBM image to PGM by averaging areas
13 !!SYNOPSIS
14
15
16 __pbmtopgm__ ''width height''
17 [[''pbmfile'']
18 !!DESCRIPTION
19
20
21 __pbmtopgm__ reads a portable bitmap as input. It outputs
22 a portable graymap in which each pixel's gray level is the
23 average the surrounding black and white input pixels. The
24 surrounding area is a rectangle of ''width'' by
25 ''height'' pixels.
26
27
28 In other words, this is a convolution. __pbmtopgm__ is
29 similar to a special case of __pnmconvol__.
30
31
32 You may need a __ppmsmooth__ step after
33 __pbmtopgm__.
34
35
36 __pbmtopgm__ has the effect of anti-aliasing bitmaps
37 which contain distinct line features.
38
39
40 __pbmtopgm__ works best with odd sample width and
41 heights.
42
43
44 You don't need __pbmtopgm__ just to use a PGM program on
45 a PBM image. Any PGM program (assuming it uses the Netpbm
46 libraries to read the PGM input) takes PBM input as if it
47 were PGM, with only the mininum and maximum gray levels. So
48 unless your convolution rectangle is bigger than one pixel,
49 you're not gaining anything with a __pbmtopgm__
50 step.
51 !!SEE ALSO
52
53
54 netpbm(1), pgmtopbm(1),
55 pbm(5)
56 !!AUTHOR
57
58
59 Copyright (C) 1990 by Angus Duggan Copyright (C) 1989 by Jef
60 Poskanzer.
61
62
63 Permission to use, copy, modify, and distribute this
64 software and its documentation for any purpose and without
65 fee is hereby granted, provided that the above copyright
66 notice appear in all copies and that both that copyright
67 notice and this permission notice appear in supporting
68 documentation. This software is provided
69 ----
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