diff options
Diffstat (limited to 'libraries/jbig2enc/jbig2.rst')
| -rw-r--r-- | libraries/jbig2enc/jbig2.rst | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/libraries/jbig2enc/jbig2.rst b/libraries/jbig2enc/jbig2.rst new file mode 100644 index 000000000000..fc17dcb3f31a --- /dev/null +++ b/libraries/jbig2enc/jbig2.rst @@ -0,0 +1,176 @@ +.. RST source for jbig2(1) man page. Convert with: +.. rst2man.py jbig2.rst > jbig2.1 +.. rst2man.py comes from the SBo development/docutils package. + +.. |version| replace:: 0.28 +.. |date| date:: + +===== +jbig2 +===== + +----------------------------------- +convert image files to JBIG2 format +----------------------------------- + +:Manual section: 1 +:Manual group: SlackBuilds.org +:Date: |date| +:Version: |version| + +SYNOPSIS +======== + +**jbig2** [*-options*] *imagefile* > *output.jb2* + +DESCRIPTION +=========== + +JBIG2 is an image compression standard from the same people who brought +you the JPEG format. It compresses 1bpp (black and white) images only. + +jbig2enc is a library that encodes JBIG2 images. + +**jbig2** is a command-line tool that uses the jbig2enc library to convert an +image to the JBIG2 format. *imagefile* can be in any format readable by +leptonica (png, jpeg, tiff, gif, webp, jp2, bmp, pnm, spix). The image +is converted to 1bbp (monochrome) before processing. + +Without the *-p*, *--pdf* option, the converted image is written to +standard output. This should be redirected to a file, normally with +the *.jb2* extension. If stdout isn't redirected to a file (or a pipe), +the JBIG2 data will be written to the terminal, which may get confused. + +There is no way to have **jbig2** read an image file on standard input. This +is by design, as it needs to seek within the file. + +All options must appear before the filename. With the generic encoder +(no *-s* option), anything after the filename is silently ignored. The +symbol encoder (*-s*) can handle multiple images (which end up as pages +in the JBIG2 file). + +The *-r*, *--refine* option mentioned in the documentation and in +the *--help* output of **jbig2** is *disabled* in this version of +**jbig2**. + +OPTIONS +======= + +.. some of these are from the HTML file, some from --help. + +-b *basename* + Output file root name when using symbol coding in PDF mode (*-s* + and *-p*). Default is **output**. + +-d, --duplicate-line-removal + When encoding generic regions each scan line can be tagged to indicate + that it's the same as the last scanline - and encoding that scanline + is skipped. This drastically reduces the encoding time (by a factor + of about 2 on some images) although it doesn't typically save any + bytes. This is an option because some versions of jbig2dec (an open + source decoding library) cannot handle this. + +-p, --pdf + The PDF spec includes support for JBIG2 (Syntax->Filters->JBIG2Decode in + the PDF references for versions 1.4 and above). However, PDF requires + a slightly different format for JBIG2 streams: no file/page headers or + trailers and all pages are numbered 1. In symbol mode the output is to + a series of files: symboltable and page-n (numbered from 0). By default + these are named **output.sym** and **output.0000**, **output.0001**, + etc. Use *-b* to change the base filename. + +-s, --symbol-mode + Use symbol encoding. Turn on for scanned text pages. + +-t *threshold* + Sets the fraction of pixels which have to match in order for + two symbols to be classed the same. This isn't strictly true, as there are + other tests as well, but increasing this will generally increase the number + of symbol classes. Default is 0.85. + +-T *threshold* + Sets the black threshold (0-255). Any gray value darker than + this is considered black. Anything lighter is considered white. + Default is 188. + +-O *outfile* + Dump a PNG of the 1 bpp image before encoding. Can be used to + test loss. + +-2, -4 + Upscale either two or four times before converting to black and + white. + +-S + Segment an image into text and non-text regions. This isn't perfect, but + running text through the symbol compressor is terrible so it's worth doing + if your input has images in it (like a magazine page). + +--image-output + Set filename to which the parts which were removed by -S are written. + Default is PNG format. + +-j, --jpeg-output + Write images from -S as JPEG instead of PNG. + +-a, --auto-thresh + Use automatic thresholding in symbol encoder. + +--no-hash + Disables use of hash function for automatic thresholding. + +-v + Be verbose. + +-V, --version + Display version number and exit. + +-h, --help + Display help and exit. + +EXIT STATUS +=========== + +**jbig2** exits with 0 (success) status if the conversion completed +OK, and non-zero status if anything went wrong. If standard output was +redirected to a file, the file will be empty or invalid when non-zero +status is returned. Diagnostic messages are printed to standard error. + +COPYRIGHT +========= + +See the file /usr/doc/jbig2enc-|version|/COPYING for license information. + +This software is a description of processes which may be patented. + +Use of this software may require patent licenses in some countries. +You are directed to annex I of the JBIG2 specification for information. + +Some information could be found at: + http://www.jpeg.org/jbig/index.html + http://www.cl.cam.ac.uk/~mgk25/jbigkit/patents/ + http://www.jpeg.org/public/fcd14492.pdf + http://itscj.ipsj.or.jp/sc29/open/29view/29n55161.doc + +AUTHORS +======= + +jbig2 and jbig2enc were written by: + Adam Langley <agl@imperialviolet.org>. + +This man page written for the SlackBuilds.org project +by B. Watson, and is licensed under the WTFPL. + +SEE ALSO +======== + +**pdf.py(1)**, **jbig2dec(1)** + +Full documentation for jbig2 and jbig2enc: + /usr/doc/jbig2enc-|version|/jbig2enc.html + +The JBIG2 specification was formerly located at: + http://www.jpeg.org/public/fcd14492.pdf + +A copy can be found here: + http://www.hlevkin.com/Standards/fcd14492.pdf |