ddjvu(1) DjVuLibre-3.5 ddjvu(1)
NAME
ddjvu - Command line DjVu decoder.
SYNOPSIS
ddjvu -format=fmt [options] [djvufile] [outputfile]
DESCRIPTION
Decode the DjVu file djvufile, produces the image file outputfile.
The DjVu data is read from the standard input when argument djvufile is
not specified or when it is equal to a single dash. Similarly, the
output data is written to the standard output when argument outputfile
is not specified or equal to a single dash. However a valid output
file name is always required when producing a TIFF or PDF file.
MAIN OPTIONS
-format=fmt
Specify the output file formats. The recognized file formats
are pbm, pgm, ppm, pnm, rle, tiff, and pdf.
* Formats pbm, pgm, and ppm respectively produce a Portable
Bitmap (PBM), Portable Graymap (PGM), or Portable Pixmap
(PPM) file. Format pnm produces a PBM, PGM, or PPM output
file according to the color content of the output image.
* Format rle produces a compact run length encoded bitonal file
that is understood by the DjVuLibre commands cjb2 and
csepdjvu.
* Format tiff produces a Tagged Image Format (TIFF) file using
lossless compression. Enabling lossy JPEG compression (see
option -quality below) often produces much smaller files.
Commands tiffcp(1) and tiffsplit(1) are useful for manipulat-
ing the resulting TIFF files.
* Format pdf produces a Portable Document Format (PDF) file.
Each page in the resulting file is represented by an image at
the specified resolution, using lossless compression.
Enabling lossy JPEG compression (see option -quality below)
often produces much smaller files. An alternate way to pro-
duce PDF file consists in first using djvups(1) and convert
the resulting PostScript file to PDF. Which method gives
better results depends on the contents of the DJVU file and
on the capabilities of the PS to PDF converter.
When option -format is not specified, the extension of argument
outputfile has no influence on the default output format.
Instead the program behavior is modified to ensure backward com-
patibility with previous versions of ddjvu. We recommend to
always specify the output format using this option.
-page=pagespec
Specify which pages should be decoded. When this option is not
specified, all pages of the documents are decoded and concate-
nated into the output file. The page specification pagespec
contains one or more comma-separated page ranges. A page range
is either a page number, or two page numbers separated by a
dash. For instance, specification 1-10 outputs pages 1 to 10,
and specification 1,3,99999-4 outputs pages 1 and 3, followed by
all the document pages in reverse order up to page 4.
-eachpage
When this option is specified, program ddjvu generates one sepa-
rate file per page named by replacing the %d specification in
outputfilename by the page number in a manner simular to the
printf(3) function.
-mode=mod
Selects which layers of the DjVu image should be rendered.
Valid rendering modes are color, black, mask, foreground, and
background.
* Rendering mode color is the default mode. When the DjVu file
is bitonal, bitonal or gray-level output is produced depend-
ing on the subsampling factor. Otherwise a color image is
produced.
* Rendering mode black is useful to extract a meaningful black
and white image. bitonal or gray-level output is produced
depending on the subsampling factor.
* Rendering modes mask, foreground, and background select spe-
cific layers of a DjVu image. These modes can fail if the
DjVu image does not contain the selected layer.
-skip Instead of aborting when encountering a corrupted page, this
option causes ddjvu to simply skip the corrupted page and con-
tinue with the next. This is useful for processing certain dam-
aged files.
RESOLUTION OPTIONS
The following options control the resolution of the output image. The
default resolution is the native resolution of the DjVu file, equiva-
lent to selecting -1.
-n Specify an integer sub-sampling factor. The dimensions of the
full output image will be n times smaller than the DjVu image
size. The legal values for argument n range from 1 to 12.
Option -1, for instance, produces an output image whose resolu-
tion is equal to the resolution of the input DjVu image file.
-subsample=n
This is equivalent to option -n.
-scale=mag
Specify a magnification factor relative to the resolution stored
in the DjVu image. Specifying magnification of 100 produces an
image suitable for displaying on a 100 dpi device such as a com-
puter screen. The magnification factor mag can also be inter-
preted as the resolution of the output image expressed in dot
per inch.
-size=wxh
Specify the size of the full output image. Rendering the full
DjVu image would create an output image whose width and height
would not exceed w and h. To change the aspect ratio, you must
also use option -aspect=no.
-aspect=yesno
This option indicates whether the image aspect ratio should be
preserved. The defaults is to preserve the aspect ration. This
option permits changes in the aspect ratio when used in combina-
tion with option -size.
OTHER OPTIONS
-verbose
Display informational messages describing the structure of the
DjVu image and the format of the output file.
-segment=wxh+x+y
Specify an image segment to render. Program ddjvu conceptually
renders the full page using the specified resolution, and then
extracts a sub-image of width w and height h, starting at posi-
tion (x,y) relative to the bottom left corner of the page. Both
operations of course happen simultaneously. Rendering a small
sub-image is much faster than rendering the complete image. The
output file will always have size wxh when this option is speci-
fied.
-quality=factor
Enables lossy JPEG compression for TIFF and PDF files. This
option only affects images that cannot be encoded using the pre-
ferred TIFF/G4 compression. Argument factor is a quantization
factor ranging from 25 to 150. See command cjpeg(1) for more
information on JPEG quantization factors. Value 80 is a good
starting point.
-quality=uncompressed
Completely disables compression in TIFF and PDF files. Although
the resulting files are often huge, this is sometimes useful for
maximal compatibility with hastily written software.
-quality=deflate
Enables DEFLATE compression for TIFF files. Images that cannot
be encoded using the preferred TIFF/G4 compression will be
encoded with DEFLATE compression if available. Otherwise the
more portable PACKBITS compression is used. Specifying this
option is not necessary for PDF files because this is the
default behavior.
DEPRECATED OPTIONS
Various options have been maintained to ensure backward compatibility
with previous versions of ddjvu. When option -format is not specified,
the program only decodes the first page of the document and the default
resolution becomes -scale=100. Options -size, -scale, -segment, and
-page accept an argument separated by a space. Options -foreground,
-background, and -black are shorthands for the -mode=mod option.
Please do not rely on these features.
EXAMPLES
Command
ddjvu -format=tiff myfile.djvu myfile.tif
decodes all pages and produces a multipage TIFF file.
Command
ddjvu -format=ppm -page=1-10 -eachpage -size=100x100 myfile.djvu
thumb%03d.ppm
produces 100x100 thumbnails for the first ten page of a document and
outputs them as PPM files named thumb001.ppm to thumb010.ppm.
CREDITS
The new version of this program was written by Leon Bottou
<leonb@users.sourceforge.net>.
This program includes code derived from program tiff2pdf, written by
Ross Finlayson and released under a BSD license.
SEE ALSO
djvu(1), djview(1), pnm(5), pbm(5), pgm(5), ppm(5), cjpeg(1), tiffs-
plit(1), tiffcp(1), printf(3)
DjVuLibre-3.5 10/19/2002 ddjvu(1)
djvulibre 3.5.27 - Generated Sat Mar 14 16:37:01 CDT 2015