198 lines
6.4 KiB
Groff
198 lines
6.4 KiB
Groff
.\" Man page generated from reStructuredText.
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.TH JBIG2 1 "2016-11-05" "0.28" "SlackBuilds.org"
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.SH NAME
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jbig2 \- convert image files to JBIG2 format
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.
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.\" RST source for jbig2(1) man page. Convert with:
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.
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.\" rst2man.py jbig2.rst > jbig2.1
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.
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.\" rst2man.py comes from the SBo development/docutils package.
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.
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.SH SYNOPSIS
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.sp
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\fBjbig2\fP [\fI\-options\fP] \fIimagefile\fP > \fIoutput.jb2\fP
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.SH DESCRIPTION
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.sp
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JBIG2 is an image compression standard from the same people who brought
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you the JPEG format. It compresses 1bpp (black and white) images only.
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.sp
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jbig2enc is a library that encodes JBIG2 images.
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.sp
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\fBjbig2\fP is a command\-line tool that uses the jbig2enc library to convert an
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image to the JBIG2 format. \fIimagefile\fP can be in any format readable by
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leptonica (png, jpeg, tiff, gif, webp, jp2, bmp, pnm, spix). The image
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is converted to 1bbp (monochrome) before processing.
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.sp
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Without the \fI\-p\fP, \fI\-\-pdf\fP option, the converted image is written to
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standard output. This should be redirected to a file, normally with
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the \fI\&.jb2\fP extension. If stdout isn\(aqt redirected to a file (or a pipe),
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the JBIG2 data will be written to the terminal, which may get confused.
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.sp
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There is no way to have \fBjbig2\fP read an image file on standard input. This
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is by design, as it needs to seek within the file.
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.sp
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All options must appear before the filename. With the generic encoder
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(no \fI\-s\fP option), anything after the filename is silently ignored. The
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symbol encoder (\fI\-s\fP) can handle multiple images (which end up as pages
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in the JBIG2 file).
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.sp
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The \fI\-r\fP, \fI\-\-refine\fP option mentioned in the documentation and in
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the \fI\-\-help\fP output of \fBjbig2\fP is \fIdisabled\fP in this version of
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\fBjbig2\fP\&.
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.SH OPTIONS
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.\" some of these are from the HTML file, some from --help.
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.
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.INDENT 0.0
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.TP
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.B \-b \fIbasename\fP
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Output file root name when using symbol coding in PDF mode (\fI\-s\fP
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and \fI\-p\fP). Default is \fBoutput\fP\&.
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.UNINDENT
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.INDENT 0.0
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.TP
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.B \-d\fP,\fB \-\-duplicate\-line\-removal
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When encoding generic regions each scan line can be tagged to indicate
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that it\(aqs the same as the last scanline \- and encoding that scanline
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is skipped. This drastically reduces the encoding time (by a factor
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of about 2 on some images) although it doesn\(aqt typically save any
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bytes. This is an option because some versions of jbig2dec (an open
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source decoding library) cannot handle this.
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.TP
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.B \-p\fP,\fB \-\-pdf
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The PDF spec includes support for JBIG2 (Syntax\->Filters\->JBIG2Decode in
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the PDF references for versions 1.4 and above). However, PDF requires
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a slightly different format for JBIG2 streams: no file/page headers or
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trailers and all pages are numbered 1. In symbol mode the output is to
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a series of files: symboltable and page\-n (numbered from 0). By default
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these are named \fBoutput.sym\fP and \fBoutput.0000\fP, \fBoutput.0001\fP,
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etc. Use \fI\-b\fP to change the base filename.
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.TP
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.B \-s\fP,\fB \-\-symbol\-mode
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Use symbol encoding. Turn on for scanned text pages.
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.UNINDENT
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.INDENT 0.0
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.TP
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.B \-t \fIthreshold\fP
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Sets the fraction of pixels which have to match in order for
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two symbols to be classed the same. This isn\(aqt strictly true, as there are
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other tests as well, but increasing this will generally increase the number
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of symbol classes. Default is 0.85.
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.TP
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.B \-T \fIthreshold\fP
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Sets the black threshold (0\-255). Any gray value darker than
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this is considered black. Anything lighter is considered white.
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Default is 188.
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.TP
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.B \-O \fIoutfile\fP
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Dump a PNG of the 1 bpp image before encoding. Can be used to
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test loss.
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.UNINDENT
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.INDENT 0.0
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.TP
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.B \-2\fP,\fB \-4
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Upscale either two or four times before converting to black and
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white.
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.TP
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.B \-S
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Segment an image into text and non\-text regions. This isn\(aqt perfect, but
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running text through the symbol compressor is terrible so it\(aqs worth doing
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if your input has images in it (like a magazine page).
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.TP
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.B \-\-image\-output
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Set filename to which the parts which were removed by \-S are written.
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Default is PNG format.
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.TP
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.B \-j\fP,\fB \-\-jpeg\-output
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Write images from \-S as JPEG instead of PNG.
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.TP
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.B \-a\fP,\fB \-\-auto\-thresh
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Use automatic thresholding in symbol encoder.
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.TP
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.B \-\-no\-hash
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Disables use of hash function for automatic thresholding.
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.TP
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.B \-v
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Be verbose.
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.TP
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.B \-V\fP,\fB \-\-version
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Display version number and exit.
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.TP
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.B \-h\fP,\fB \-\-help
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Display help and exit.
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.UNINDENT
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.SH EXIT STATUS
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.sp
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\fBjbig2\fP exits with 0 (success) status if the conversion completed
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OK, and non\-zero status if anything went wrong. If standard output was
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redirected to a file, the file will be empty or invalid when non\-zero
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status is returned. Diagnostic messages are printed to standard error.
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.SH COPYRIGHT
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.sp
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See the file /usr/doc/jbig2enc\-0.28/COPYING for license information.
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.sp
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This software is a description of processes which may be patented.
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.sp
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Use of this software may require patent licenses in some countries.
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You are directed to annex I of the JBIG2 specification for information.
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.INDENT 0.0
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.TP
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.B Some information could be found at:
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\fI\%http://www.jpeg.org/jbig/index.html\fP
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\fI\%http://www.cl.cam.ac.uk/~mgk25/jbigkit/patents/\fP
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\fI\%http://www.jpeg.org/public/fcd14492.pdf\fP
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\fI\%http://itscj.ipsj.or.jp/sc29/open/29view/29n55161.doc\fP
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.UNINDENT
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.SH AUTHORS
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.INDENT 0.0
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.TP
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.B jbig2 and jbig2enc were written by:
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Adam Langley <\fI\%agl@imperialviolet.org\fP>.
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.UNINDENT
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.sp
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This man page written for the SlackBuilds.org project
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by B. Watson, and is licensed under the WTFPL.
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.SH SEE ALSO
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.sp
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\fBpdf.py(1)\fP, \fBjbig2dec(1)\fP
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.INDENT 0.0
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.TP
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.B Full documentation for jbig2 and jbig2enc:
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/usr/doc/jbig2enc\-0.28/jbig2enc.html
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.TP
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.B The JBIG2 specification was formerly located at:
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\fI\%http://www.jpeg.org/public/fcd14492.pdf\fP
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.TP
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.B A copy can be found here:
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\fI\%http://www.hlevkin.com/Standards/fcd14492.pdf\fP
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.UNINDENT
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.\" Generated by docutils manpage writer.
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