1G3topbm User Manual(0)                                  G3topbm User Manual(0)
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NAME

6       g3topbm - convert a Group 3 fax file into a PBM image
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SYNOPSIS

10       g3topbm    [-kludge]   [-reversebits]   [-stretch]   [-width=pixels   |
11       paper_size={A3|A4|A5|A6|B4}] [-stop_error] [g3file]
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13       Minimum unique abbreviation of option is acceptable.  You may use  dou‐
14       ble  hyphens  instead  of single hyphen to denote options.  You may use
15       white space in place of the equals sign to separate an option name from
16       its value.
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DESCRIPTION

20       This program is part of Netpbm(1).
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22       g3topbm reads a Group 3 fax file with MH (Modified Huffman) compression
23       as input and produces a PBM image as output.
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25       g3topbm tolerates various  deviations  from  the  standard,  so  as  to
26       recover some of the image if there was a transmission error.  One thing
27       it tolerates is lines of varying length.  The standard requires all the
28       lines  to be the same length; g3topbm makes the output image as wide as
29       the longest line in the input and pads the others  on  the  right.   It
30       warns you when it does this.
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32       You  can  use  the  stop_error  option  to make g3topbm insist on valid
33       input.
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35       There is no Netpbm program that understands the other G3  fax  compres‐
36       sion methods: MR (Modified Read) and MMR (Modified Modified Read).
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38       Note  that  the  Group 3 fax file format does not include any kind of a
39       signature so that g3topbm might verify it's actually looking  at  a  G3
40       file  or that the compression method is MH.  The program will interpret
41       any sequence of bytes you give it as if it is G3 and,  while  typically
42       issuing a lot of error messages about the file not conforming to the G3
43       MH format, will produce output (unless you use -stoperror).  In partic‐
44       ular,  if  you  feed g3topbm an MR or MMR file, it will not tell you of
45       your mistake.
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47       There are subformats of TIFF that use the Group 3 fax encodings inside.
48       See tifftopnm.
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OPTIONS

53       -kludge
54              Tells  g3topbm  to ignore the first few lines of the file; some‐
55              times fax files have some junk at the beginning.
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58       -reversebits
59              Tells g3topbm to interpret bits least-significant first, instead
60              of  the  default  most-significant  first.   Apparently some fax
61              modems do it one way and others do it the other way.  If you get
62              a  whole  bunch  of  "bad  code  word"  messages, try using this
63              option.
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66       -stretch
67              This option tells g3topbm to stretch  the  image  vertically  by
68              duplicating  each row.  This is for the low-quality transmission
69              mode.
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72       -width=pixels
73              This option tells g3topbm that the image is supposed to be  pix‐
74              els  pixels  wide.   If any line in it is not that size, g3topbm
75              issues a warning or fails,  depending  on  whether  you  specify
76              -stop_error.
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78              You cannot specify both -width and -paper_size.
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80              This option was new in Netpbm 10.33 (March 2006).
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83       -paper_size={A3,A4,A5,A6,B4}
84              This option tells g3topbm for what size paper this image is sup‐
85              posed to be formatted.  g3topbm uses the width of the paper  the
86              same  way  as  with the -width option.  g3topbm does not use the
87              height of the paper for anything.
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89              You cannot specify both -width and -paper_size.
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91              This option was new in Netpbm 10.33 (March 2006).
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94       -stop_error
95              This option tells g3topbm to fail when it finds a problem in the
96              input.   "Fail"  means  it terminates with a nonzero status code
97              with the contents of the output file undefined.
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99              If you don't specify this option, g3topbm does its best to  work
100              around input errors and salvage as much of the image as possible
101              in the output image.  It first tries to resynchronize to a later
102              line  by searching for the next End Of Line marker, skipping any
103              lines or partial lines in between.  It saves  the  beginning  of
104              the line in which it encountered the problem.  If the input file
105              ends prematurely, g3topbm produces output containing  the  lines
106              up to where it encountered the problem.
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108              g3topbm  issues  warning  messages when it continues in spite of
109              input errors.
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111              This option was new in Netpbm 10.24 (August 2004).  Before that,
112              g3topbm  always  failed  when  it  encountered premature EOF and
113              never failed when it encountered other problems.
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SEE ALSO

120       pbmtog3(1), tifftopnm(1), pbm(1) fax formats(1)
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DOCUMENT SOURCE

123       This manual page was generated by the Netpbm tool 'makeman'  from  HTML
124       source.  The master documentation is at
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126              http://netpbm.sourceforge.net/doc/g3topbm.html
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128netpbm documentation           03 December 2008         G3topbm User Manual(0)
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