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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.  The resulting file uses the  best  available
                 lossless  compression  model.  Enabling lossy JPEG compression (see option -quality below) often pro-
                 duces 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 repre-
                 sented 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 out-
                 put 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.

       -skip  Instead of aborting when encountering a corrupted page, this option causes ddjvu to simply skip the cor-
              rupted page and continue with the next.  This is useful for processing certain damaged files.


RESOLUTION OPTIONS
       The following options control the resolution of the output image.  The default resolution is the native resolu-
       tion 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 magnifi-
              cation  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  speci-
              fied resolution, and then extracts a sub-image of width w and height h, starting at position (x,y) rela-
              tive 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 rang-
              ing 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.


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 reso-
       lution 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 Leon Bottou <leonbATusers.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)



DjVuLibre-3.5                     10/19/2002                          DDJVU(1)