DDJVU
Section: DjVuLibre-3.5 (1)
Updated: 10/19/2002
Index
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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 (PGM) 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.
The resulting file uses the best available
lossless compression model.
Enabling lossy JPEG compression (see option
-quality
below) often produces much smaller files.
Commands
tiffcp(1)
and
tiffsplit(1)
are useful for manipulating 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 the best available lossless compression model.
Enabling lossy JPEG compression (see option
-quality
below) often produces much smaller files.
An alternate way to produce 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 compatibility 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 concatenated 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.
- -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 depending 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 specific layers of a DjVu image.
These modes can fail if the DjVu image does
not contain the selected layer.
RESOLUTION OPTIONS
The following options control the resolution of the output image.
The default resolution is the native resolution of the DjVu file,
equivalent 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 resolution
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 computer screen.
The magnification factor
mag
can also be interpreted 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 combination 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 position
(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 specified.
- -quality=factor
-
Enables lossy compression in TIFF and PDF files.
Without this option, TIFF or PDF output files always
use lossless compression or no compression.
Argument
factor
specifies a JPEG 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.
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 -size=100x100 myfile.djvu -
produces a thumbnail for the first page of a document and
outputs it as a PPM file on the standard output.
CREDITS
The new version of this program was written
by Léon 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),
tiffsplit(1),
tiffcp(1)
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- MAIN OPTIONS
-
- RESOLUTION OPTIONS
-
- OTHER OPTIONS
-
- DEPRECATED OPTIONS
-
- EXAMPLES
-
- CREDITS
-
- SEE ALSO
-
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Time: 09:25:01 GMT, February 19, 2009