NAME

       ppmtoacad - convert PPM to Autocad database or slide

SYNOPSIS

       ppmtoacad

       [-dxb]

       [-poly]

       [-background color]

       [-white]

       [-aspect ratio]

       [-8]

       [ppmfile]

DESCRIPTION

       This program is part of Netpbm(1).

       ppmtoacad  reads  a  PPM  image  as  input  and  produces an Autocad® slide file or binary
       database import (.dxb) file as output.  If you don't specify ppmfile, ppmtoacad takes  the
       input from Standard Input.

       (Typographical   note:  the  name  of  Autocad  is  often  rendered  as  AutoCAD.   Netpbm
       documentation uses standard American typography, wherein that  is  not  a  valid  form  of
       capitalization).

OPTIONS

       In addition to the options common to all programs based on libnetpbm (most notably -quiet,
       see
        Common Options ⟨index.html#commonoptions⟩ ), ppmtoacad recognizes the  following  command
       line options:

       You may abbreviate any option to its shortest unique prefix.

       -dxb   ppmtoacad writes an Autocad binary database import (.dxb) file.  You read this file
              with the DXBIN command and, once loaded, it becomes part of the Autocad geometrical
              database,  so  you  can  view  and edit it like any other object.  Each sequence of
              identical pixels becomes a separate object in the database; this can result in very
              large  Autocad drawing files.  However, if you want to trace over a bitmap, it lets
              you zoom and pan around the bitmap as you wish.

       -poly  If you don't specify the -dxb option, ppmtoacad generates an  Autocad  slide  file.
              Normally  each  row  of  pixels  is  represented by an Autocad line entity.  If you
              specify -poly, ppmtoacad renders the pixels as filled polygons.  If  you  view  the
              slide  on  a  display with higher resolution than the source image, this will cause
              the pixels to expand instead of appearing as  discrete  lines  against  the  screen
              background color.  Regrettably, this representation yields slide files which occupy
              more storage space and take longer to display.

       -background color
              Most Autocad display drivers can be configured to use any available  color  as  the
              screen  background.   Some  users  prefer  a black screen background, others white,
              while splinter  groups  advocate  burnt  ocher,  tawny  puce,  and  shocking  gray.
              Discarding  pixels  whose  closest  Autocad  color  representation  is equal to the
              background color can substantially reduce the size of the Autocad database or slide
              file  needed  to  represent  a bitmap.  If you don't specify -background, ppmtoacad
              assumes the screen background color to be black.  You may specify any Autocad color
              number  as  the  screen  background; ppmtoacad assumes color numbers to specify the
              hues defined in the standard Autocad 256 color palette.

       -white Since many Autocad users choose a white screen background, this option is  provided
              as a short-cut.  Specifying -white is identical in effect to -background 7.

       -aspect ratio
              If  the  source  image  had non-square pixels (which means it is not standard PPM),
              specify the ratio of the pixel width to pixel  height  as  ratio.   ppmtoacad  will
              correct  the resulting slide or .dxb file so that pixels on the Autocad screen will
              be square.  For example, to correct an image made for a  320x200  VGA/MCGA  screen,
              specify -aspect 0.8333.

       -8     Restricts the colors in the output file to the 8 RGB shades.

RESTRICTIONS

       Autocad  has  a  fixed  palette  of  256 colors, distributed along the hue, lightness, and
       saturation axes.  So it may poorly  render  images  which  contain  many  nearly-identical
       colors, or colors not closely approximated by Autocad's palette.

       ppmtoacad  works  best  if the system displaying its output can display the full 256 color
       Autocad palette.  Monochrome, 8 color, and 16 color configurations will produce less  than
       optimal results.

       When  creating  a  .dxb  file  or a slide file with the -poly option, ppmtoacad finds both
       vertical and horizontal runs of identical pixels and consolidates  them  into  rectangular
       regions  to  reduce  the size of the output file.  This is effective for images with large
       areas of constant color but it's no substitute for true raster to vector  conversion.   In
       particular, this process does not optimize thin diagonal lines at all.

       Output files can be huge.

SEE ALSO

       Autocad  Reference  Manual:  Slide File Format and Binary Drawing Interchange (DXB) Files,
       ppm(1)

AUTHOR

       John Walker
       Autodesk SA
       Avenue des Champs-Montants 14b
       CH-2074 MARIN
       Suisse/Schweiz/Svizzera/Svizra/Switzerland
           Usenet:kelvin@Autodesk.com
           Fax:038/33 88 15
           Voice:038/33 76 33

       Permission to use, copy, modify, and distribute this software and  its  documentation  for
       any  purpose  and  without  fee is hereby granted, without any conditions or restrictions.
       This software is provided "as is" without express or implied warranty.

       Autocad and Autodesk are registered trademarks of Autodesk, Inc.

DOCUMENT SOURCE

       This manual page was generated by the Netpbm tool 'makeman' from HTML source.  The  master
       documentation is at

              http://netpbm.sourceforge.net/doc/ppmtoacad.html