1CSEPDJVU(1)                      DjVuLibre-3.5                     CSEPDJVU(1)
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NAME

6       csepdjvu - DjVu encoder for separated data files.
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SYNOPSIS

10       csepdjvu  [options] [sepfiles]... outputdjvufile
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DESCRIPTION

14       This  program creates a DjVuDocument file outputdjvufile from separated
15       data files sepfiles.  It can read  separated  data  from  the  standard
16       input  when  given  a  single  dash  instead of the separated data file
17       names.  This feature is intended for pre-processing programs that  push
18       separated data into csepdjvu via a pipe.
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20       Each  separated data file represents one or more page images.  When the
21       program arguments specify multiple pages, all the pages are encoded and
22       saved  as  a  bundled  multi-page document.  When the program arguments
23       specify a single page, the page is encoded and saved as a  single  page
24       file.
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OPTIONS

28       -d n   Specify  the resolution information encoded into the output file
29              expressed in dots per inch. The resolution  information  encoded
30              in  DjVu  files  determine how the decoder scales the image on a
31              particular display.  Meaningful resolutions  range  from  25  to
32              6000.  The default value is 300 dpi.
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34       -q n,...,n
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36       -q n+...+n
37              Specify  the  encoding  quality  of  the IW44 encoded background
38              layer.  The option argument contain several  integers  (one  per
39              chunk)  separated  by  either  commas or pluses.  This option is
40              similar to option -slice of program c44.  Please  refer  to  the
41              c44(1)  man  page  for  additional details.  The default quality
42              specification is -q 72,83,93,103.
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44              This option does not apply to uniformly  white  background  that
45              were  not  specified by the separated data but are called for by
46              the DjVu specification.  Such background images always  come  at
47              the  lowest possible resolution and with a standard quality set‐
48              ting that ensures the color uniformity.
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50       -t     Program csepdjvu interprets certain comments  in  the  separated
51              file  to  construct  a  hidden text layer in the DjVu file. This
52              layer records the location of each word for  hiliting  purposes.
53              This  option reduces the file size by simply recording the loca‐
54              tion of each line.
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56       -v     Display a brief message describing each page.
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58       -vv    Display extensive informational messages during encoding.
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SEPARATED DATA FILE FORMAT

62       Each separated data file contains a concatenation of one or more  sepa‐
63       rated  page images.  Each page is logically represented by a foreground
64       image with a transparent  color  and  by  a  background  image  visible
65       through the transparent pixels.  The data for each separated page image
66       is the concatenation of the following data blocks:
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68       *  A foreground image encoded using either the "Color  RLE  format"  or
69          the "Bitonal RLE format".  These formats are described later in this
70          section.
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72       *  An optional background image encoded as a "Portable Pixmap" ( PPM ).
73          This  well  known  format  is summarized later in this section.  The
74          absence of a background image  simply  indicates  that  a  uniformly
75          white background should be assumed.
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77       *  An arbitrary number of comment lines starting with character "#" and
78          terminated by a linefeed character. Comment lines whose  first  word
79          starts  with a capital letter have special meanings documented later
80          in this document.
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82       The dimensions (width and height)  of  the  background  image  must  be
83       obtained by rounding up the quotient of the foreground image dimensions
84       by an integer reduction factor ranging  from  1  to  12.   Assume,  for
85       instance,  that  the  width of the foreground is 2507 and the reduction
86       factor is 3.  The width of the background image  will  be  the  integer
87       ratio (2507+2)/3.
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90   Color RLE format
91       The  Color  RLE format is a simple run-length encoding scheme for color
92       images with a limited number of distinct colors.  The data always begin
93       with  a  text header composed of the two characters "R6", the number of
94       columns, the number of rows, and the number of color  palette  entries.
95       All numbers are expressed in decimal ASCII.  These four items are sepa‐
96       rated by blank characters (space, tab, carriage return, or linefeed) or
97       by  comment lines introduced by character "#".  The last number is fol‐
98       lowed by exactly one character which usually is a linefeed character.
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100       The header is followed by the color palette containing three bytes  per
101       color  entry.   The bytes represent the red, green, and blue components
102       of the color.
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104       The palette is followed by a collection of four  bytes  integers  (most
105       significant  bit  first)  representing runs of pixels with an identical
106       color.  The twelve upper bits of this integer indicate the index of the
107       run  color  in the palette entry.  The twenty lower bits of the integer
108       indicate  the  run  length.   Color  indices  greater  than  0xff0  are
109       reserved.  Color index 0xfff is used for transparent runs.  Each row is
110       represented by a sequence of runs whose lengths add  up  to  the  image
111       width.   Rows  are  encoded  starting  with the top row and progressing
112       toward the bottom row.
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115   Bitonal RLE format
116       The Bitonal RLE format is  a  simple  run-length  encoding  scheme  for
117       bitonal  images.   The data always begin with a text header composed of
118       the two characters "R4", the number of columns, and the number of rows.
119       All numbers are expressed in decimal ASCII.  These three items are sep‐
120       arated by blank characters (space, tab, carriage return,  or  linefeed)
121       or  by  comment  lines introduced by character "#".  The last number is
122       followed by exactly one character which usually is a  linefeed  charac‐
123       ter.
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125       The  rest  of  the  file encodes a sequence of numbers representing the
126       lengths of alternating runs of transparent and black pixels.  Lines are
127       encoded  starting  with  the top line and progressing toward the bottom
128       line.  Each line starts with a white run. The decoder knows that a line
129       is  finished  when the sum of the run lengths for that line is equal to
130       the number of columns in the image.  Numbers in range 0 to 191 are rep‐
131       resented  by a single byte in range 0x00 to 0xbf.  Numbers in range 192
132       to 16383 are represented by a two byte sequence:  the  first  byte,  in
133       range  0xc0  to 0xff, encodes the six most significant bits of the num‐
134       ber, the second byte encodes the remaining eight bits  of  the  number.
135       This  scheme  allows  for  runs of length zero, which are useful when a
136       line starts with a black pixel, and when a very long run (whose  length
137       exceeds 16383) must be split into smaller runs.
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140   Portable Pixmap (PPM) format
141       The  Portable  Pixmap  format  is  a well known format for representing
142       color images.  Check the ppm(1) man page for complete information.
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144       The data always begin with a text header composed of the two characters
145       "P6",  the number of columns, the number of rows, and the maximal value
146       of a color component (usually 255).  All numbers are expressed in deci‐
147       mal ASCII.  These three items are separated by blank characters (space,
148       tab, carriage return, or linefeed) or by comment  lines  introduced  by
149       character  "#".   The  last number is followed by exactly one character
150       which usually is a linefeed character.
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152       The rest of the file encodes all the pixels.  Each pixel is represented
153       by  three  bytes  representing the red, green and blue component of the
154       pixel.  Pixels are ordered in left to right, top to bottom.
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157   Comments in separated files
158       Each page is followed by an arbitrary number of comment lines  starting
159       with  character  "#"  and  terminated by a linefeed character.  Comment
160       lines whose first word starts with a capital letter have special  mean‐
161       ings. The following constructs are currently defined:
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163       *  # T px:py dx:dy wxh+x+y (string)
164          This  constructs  indicates  that  the  piece of text string must be
165          associated with an area of size wxh at position x,y relative to  the
166          lower left corner of the page.  The string is UTF-8 encoded. Special
167          characters can be escaped as in PostScript using the backslash char‐
168          acter.   Integers  px,  and py represent the position of the current
169          point on the text baseline before the text was  drawn.  The  drawing
170          operation  then  moves the current point by dx, and dy pixels.  When
171          such comments are present, csepdjvu produces a hidden text layer for
172          the corresponding pages.
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174       *  # L wxh+x+y (url)
175          This  construct  indicates  that  an  hyperlink to url url should be
176          associated with area of size wxh at position x,y.   When  such  com‐
177          ments  are present, csepdjvu produces pages with an annotation chunk
178          containing the specified hyperlinks.
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180       *  # B count (string) (#pageno)
181          This constructs provides outline information for the  document.   An
182          outline entry entitled string is associated with page pageno.  Inte‐
183          ger count indicates how many of the following outline  entries  must
184          be  attached to the current entry as subentries.  When such comments
185          are present in the first page csepdjvu produces an navigation  chunk
186          with the specified outline.
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CREDITS

190       This  program was initially written by Léon Bottou <leonb@users.source‐
191       forge.net> and was improved by Bill  Riemers  <docbill@sourceforge.net>
192       and many others.
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SEE ALSO

196       djvu(1), ppm(5), c44(1)
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200DjVuLibre-3.5                     10/11/2001                       CSEPDJVU(1)
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