djvudigital (1)

Leading comments

Copyright (c) 2001-2003 Leon Bottou, Yann Le Cun, Patrick Haffner,
Copyright (c) 2001 AT&T Corp., and Lizardtech, Inc.

This is free documentation; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of
the License, or (at your option) any later version.

The GNU General Public License's references to "object code"
and "executables" are to be interpreted as the output of any
document formatti...

(The comments found at the beginning of the groff file "man1/djvudigital.1".)

NAME

djvudigital - creates DjVu files from PS or PDF files.

SYNOPSIS

djvudigital [options] inputfile [outputfile]

DESCRIPTION

This program creates a DjVu file from the PostScript (.ps), GZipped PostScript (.ps.gz), Encapsulated PostScript (.eps), or Portable Document Format (.pdf) file inputfile.
The output file name is either given by argument outputfile or generated by replacing the input file name suffixes by the DjVu suffix (.djvu).

PREREQUISITES

This program depends on a specific GhostScript driver. If your GhostScript program does not provide this driver, please check djvu.sourceforge.net/gsdjvu.html.

OPTIONS

--verbose, -v

Displays more informational messages while converting the file.

--quiet, -q

Do not display informational messages while converting the file.

--dpi=resolution

Specify the desired resolution to resolution dots per inch. The default is 300 dpi.

--psrotate=angle

Rotate the PostScript file by angle degrees clockwise. Only the values 0, 90, 180, and 270 are supported. This option only applies to PostScript files. PDF files are always converted according to their native orientation.

--epsf=disposition

Specify how to handle Encapsulated PostScript files. Argument disposition can take the values crop, fit, and ignore. The default disposition crop creates a DjVu file whose size matches the bounding box of the Encapsulated PostScript file. Value fit rescales the graphics to the default page size. Value ignore disables all Encapsulated PostScript specific code. This option requires Ghostscript 7.07 or better.

--exact-color

Enables a more accurate rendering of the colors. This option requires GhostScript 6.52 or better.

--threshold=thres

Specify a threshold for the foreground/background separation code. Acceptable values of thres range from 0 to 100. Larger values place more information into the foreground layer. The default threshold value is 80.

--bg-subsample=sub

Specify the background subsampling ratio. Argument sub must be an integer between 1 and 6. The default value is 3.

--bg-slices=n+...+n

Specify the encoding quality of the background layer. The syntax for the argument is similar to that described for the -slice option of command c44. The default is 72+11+10+10.

--fg-colors=ncolors

Specify the maximum number of distinct colors in the foreground layer. Argument ncolors can take integer values between 1 and 4000. The default value is 256.

--fg-image-colors=ncolors

Specify the maximum number of distinct colors in an image for considering encoding it into the foreground layer. Argument ncolors can take integer values between 1 and 4000. The default value is 256.

--words

Extract the text from the PostScript code and incorporates this information into the DjVu file. This option records the location of every word.

--lines

Extract the text from the PostScript code and incorporates this information into the DjVu file. This option saves a few bytes by only recording the location of each line.

--gsarg=arg1[,arg2,...,argN]

Insert extra arguments on the GhostScript command line.

--cseparg=arg1[,arg2,...,argN]

Insert extra arguments on the command line of program csepdjvu or msepdjvu.

--poppler=keywords

This option causes djvudigital to extract additional information from PDF files using the tool pdftotext that comes bundled with the Poppler library. Selected information is then added to the djvu file as a postprocessing step. This option is ignored when the input file is not a PDF file. Argument keywords is a comma separated list of keywords. When this list contains keyword meta, the metadata extracted by pdftotext is inserted into the djvu file. When this list contains keyword text, the textual information extracted by pdftotext is inserted into the djvu file, possibly replacing the information gathered using the options --words or --lines. This is useful for instance when a scanned PDF file contains a hidden text layer that is not recognized by Ghostscript and therefore not passed to the djvudigital backend.

--sepfile

Produces a separated data file instead of a DjVu file. Program csepdjvu can then convert the separated data file into a DjVu file.

--check

Display the names of the two auxiliary programs found by djvudigital, namely a suitable ghostscript interpreter and a suitable backend encoder. See the next two section for details.

--dryrun

Simply display the ghostscript command line generated by djvudigital without running it. No output file is produced

--help

Display the manual page for djvudigital.

GHOSTSCRIPT ISSUES

Program djvudigital internally relies on a specific Ghostscript driver named djvusep. This driver analyzes the logical structure of the sequence of PostScript rendering commands and decides to execute each command into either the foreground or the background layer. The GhostScript driver produces a separated data file that is then compressed using the DjVuLibre program csepdjvu.
Before processing the input file, program djvudigital searches a Ghostscript executable providing the djvusep driver. The search starts with the file specified by the environment variable GSDJVU and continues with command line executables named gs and gsdjvu.
The DjVuLibre source code contains instruction to compile such a GhostScript executable. More information can be obtained from djvu.sourceforge.net/gsdjvu.html.

CSEPDJVU ISSUES

The output of the djvusep GhostScript driver must be processed by the DjVuLibre program csepdjvu. This program can also be replaced by the the proprietary Lizardtech program msepdjvu. Before processing the input file, program djvudigital searches such an executable. The search starts with the file specified by the environment variable CSEPDJVU and continues with command line executables named msepdjvu and csepdjvu.

OTHER PROGRAMS

The option --poppler=keywords relies on the tool pdftotext that comes with the Poppler library and the tool djvused that comes with djvulibre. Only recent versions of pdftotext that accept the option -bbox are supported. Both tools are searched by first trying the files specified by the environment variables PDFTOTEXT and DJVUSED, and then trying executables named pdftotext or djvused found along the shell executable path.

CREDITS

The first version of this converter was written by L'eon Bottou <leonb@users.sourceforge.net> in AT&T Labs. The DjVuLibre version is derived from code graciously released by Lizardtech in January 2004.

BUGS

Program djvudigital can only process input files that GhostScript can process properly.

SEE ALSO

djvu(1), csepdjvu(1), c44(1), gs(1), gzip(1)