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csepdjvu(1)                      DjVuLibre-3.5                     csepdjvu(1)




NAME

       csepdjvu - DjVu encoder for separated data files.



SYNOPSIS

       csepdjvu  [options] [sepfiles]... outputdjvufile



DESCRIPTION

       This  program creates a DjVuDocument file outputdjvufile from separated
       data files sepfiles.  It can read  separated  data  from  the  standard
       input  when  given  a  single  dash  instead of the separated data file
       names.  This feature is intended for pre-processing programs that  push
       separated data into csepdjvu via a pipe.

       Each  separated data file represents one or more page images.  When the
       program arguments specify multiple pages, all the pages are encoded and
       saved  as  a  bundled  multi-page document.  When the program arguments
       specify a single page, the page is encoded and saved as a  single  page
       file.



OPTIONS

       -d n   Specify  the resolution information encoded into the output file
              expressed in dots per inch. The resolution  information  encoded
              in  DjVu  files  determine how the decoder scales the image on a
              particular display.  Meaningful resolutions  range  from  25  to
              6000.  The default value is 300 dpi.

       -q n,...,n

       -q n+...+n
              Specify  the  encoding  quality  of  the IW44 encoded background
              layer.  The option argument contain several  integers  (one  per
              chunk)  separated  by  either  commas or pluses.  This option is
              similar to option -slice of program c44.  Please  refer  to  the
              c44(1)  man  page  for  additional details.  The default quality
              specification is -q 72,83,93,103.

              This option does not apply to uniformly  white  background  that
              were  not  specified by the separated data but are called for by
              the DjVu specification.  Such background images always  come  at
              the  lowest possible resolution and with a standard quality set-
              ting that ensures the color uniformity.

       -t     Program csepdjvu interprets certain comments  in  the  separated
              file  to  construct  a  hidden text layer in the DjVu file. This
              layer records the location of each word for  hiliting  purposes.
              This  option reduces the file size by simply recording the loca-
              tion of each line.

       -v     Display a brief message describing each page.

       -vv    Display extensive informational messages during encoding.



SEPARATED DATA FILE FORMAT

       Each separated data file contains a concatenation of one or more  sepa-
       rated  page images.  Each page is logically represented by a foreground
       image with a transparent  color  and  by  a  background  image  visible
       through the transparent pixels.  The data for each separated page image
       is the concatenation of the following data blocks:

       *  A foreground image encoded using either the "Color  RLE  format"  or
          the "Bitonal RLE format".  These formats are described later in this
          section.

       *  An optional background image encoded as a "Portable Pixmap" ( PPM ).
          This  well  known  format  is summarized later in this section.  The
          absence of a background image  simply  indicates  that  a  uniformly
          white background should be assumed.

       *  An arbitrary number of comment lines starting with character "#" and
          terminated by a linefeed character. Comment lines whose  first  word
          starts  with a capital letter have special meanings documented later
          in this document.

       The dimensions (width and height)  of  the  background  image  must  be
       obtained by rounding up the quotient of the foreground image dimensions
       by an integer reduction factor ranging  from  1  to  12.   Assume,  for
       instance,  that  the  width of the foreground is 2507 and the reduction
       factor is 3.  The width of the background image  will  be  the  integer
       ratio (2507+2)/3.


   Color RLE format
       The  Color  RLE format is a simple run-length encoding scheme for color
       images with a limited number of distinct colors.  The data always begin
       with  a  text header composed of the two characters "R6", the number of
       columns, the number of rows, and the number of color  palette  entries.
       All numbers are expressed in decimal ASCII.  These four items are sepa-
       rated by blank characters (space, tab, carriage return, or linefeed) or
       by  comment lines introduced by character "#".  The last number is fol-
       lowed by exactly one character which usually is a linefeed character.

       The header is followed by the color palette containing three bytes  per
       color  entry.   The bytes represent the red, green, and blue components
       of the color.

       The palette is followed by a collection of four  bytes  integers  (most
       significant  bit  first)  representing runs of pixels with an identical
       color.  The twelve upper bits of this integer indicate the index of the
       run  color  in the palette entry.  The twenty lower bits of the integer
       indicate  the  run  length.   Color  indices  greater  than  0xff0  are
       reserved.  Color index 0xfff is used for transparent runs.  Each row is
       represented by a sequence of runs whose lengths add  up  to  the  image
       width.   Rows  are  encoded  starting  with the top row and progressing
       toward the bottom row.


   Bitonal RLE format
       The Bitonal RLE format is  a  simple  run-length  encoding  scheme  for
       bitonal  images.   The data always begin with a text header composed of
       the two characters "R4", the number of columns, and the number of rows.
       All numbers are expressed in decimal ASCII.  These three items are sep-
       arated by blank characters (space, tab, carriage return,  or  linefeed)
       or  by  comment  lines introduced by character "#".  The last number is
       followed by exactly one character which usually is a  linefeed  charac-
       ter.

       The  rest  of  the  file encodes a sequence of numbers representing the
       lengths of alternating runs of transparent and black pixels.  Lines are
       encoded  starting  with  the top line and progressing toward the bottom
       line.  Each line starts with a white run. The decoder knows that a line
       is  finished  when the sum of the run lengths for that line is equal to
       the number of columns in the image.  Numbers in range 0 to 191 are rep-
       resented  by a single byte in range 0x00 to 0xbf.  Numbers in range 192
       to 16383 are represented by a two byte sequence:  the  first  byte,  in
       range  0xc0  to 0xff, encodes the six most significant bits of the num-
       ber, the second byte encodes the remaining eight bits  of  the  number.
       This  scheme  allows  for  runs of length zero, which are useful when a
       line starts with a black pixel, and when a very long run (whose  length
       exceeds 16383) must be split into smaller runs.


   Portable Pixmap (PPM) format
       The  Portable  Pixmap  format  is  a well known format for representing
       color images.  Check the ppm(1) man page for complete information.

       The data always begin with a text header composed of the two characters
       "P6",  the number of columns, the number of rows, and the maximal value
       of a color component (usually 255).  All numbers are expressed in deci-
       mal ASCII.  These three items are separated by blank characters (space,
       tab, carriage return, or linefeed) or by comment  lines  introduced  by
       character  "#".   The  last number is followed by exactly one character
       which usually is a linefeed character.

       The rest of the file encodes all the pixels.  Each pixel is represented
       by  three  bytes  representing the red, green and blue component of the
       pixel.  Pixels are ordered in left to right, top to bottom.


   Comments in separated files
       Each page is followed by an arbitrary number of comment lines  starting
       with  character  "#"  and  terminated by a linefeed character.  Certain
       comment lines have special meanings. In the following  constructs,  all
       the  strings are UTF-8 encoded and represent in the style of Postscript
       strings, that is, surrounded with parenthesis and using C-style  escape
       sequences introduced by a backslash.

       *  # T px:py dx:dy wxh+x+y (string)
          Such  a comment line indicates that the piece of text string must be
          associated with an area of size wxh at position x,y relative to  the
          lower  left  corner  of the page.  Integers px, and py represent the
          position of the current point on the text baseline before  the  text
          was drawn. The drawing operation then moves the current point by dx,
          and dy pixels.  When such comments are present, csepdjvu produces  a
          hidden text layer for the corresponding pages.

       *  # L wxh+x+y (url)
          Such a comment line indicates that an hyperlink to url url should be
          associated with area of size wxh at position x,y.   When  such  com-
          ments  are present, csepdjvu produces pages with an annotation chunk
          containing the specified hyperlinks.

       *  # B count (string) (#pageno)
          Such a comment line provides outline information for  the  document.
          An  outline  entry  entitled  string is associated with page pageno.
          Integer count indicates how many of the  following  outline  entries
          must be attached to the current entry as subentries.  When such com-
          ments are present in the first page csepdjvu produces an  navigation
          chunk with the specified outline.

       *  # P (string)
          Such a comment line provides a title string for the current page.


CREDITS

       This  program was initially written by Leon Bottou <leonb@users.source-
       forge.net> and was improved by Bill  Riemers  <docbill@sourceforge.net>
       and many others.



SEE ALSO

       djvu(1), ppm(5), c44(1)



DjVuLibre-3.5                     10/11/2001                       csepdjvu(1)

djvulibre 3.5.28 - Generated Sat Dec 12 09:16:22 CST 2020
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