ppmtoacad(1)                                         ppmtoacad(1)

NAME
       ppmtoacad - convert portable pixmap to AutoCAD database or
       slide

SYNOPSIS
       ppmtoacad [-dxb] [-poly] [-background colour] [-white]
               [-aspect ratio] [-8] [ppmfile]

DESCRIPTION
       Reads  a portable pixmap as input.  Produces an AutoCAD(R)
       slide file or binary database import (.dxb) file  as  out-
       put.  If no ppmfile is specified, input is read from stan-
       dard input.

OPTIONS
       -dxb   An AutoCAD binary database import  (.dxb)  file  is
              written.   This file is read with the DXBIN command
              and, once loaded, becomes part of the AutoCAD  geo-
              metrical database and can be viewed and edited like
              any other object.  Each sequence of identical  pix-
              els 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  the -dxb option is not specified, the output of
              ppmtoacad is an AutoCAD slide file.  Normally  each
              row  of  pixels  is  represented by an AutoCAD line
              entity.  If -poly is selected, the pixels are  ren-
              dered  as  filled polygons.  If the slide is viewed
              on a display with higher resolution than the source
              pixmap,  this  will  cause  the  pixels  to  expand
              instead of appearing as discrete lines against  the
              screen background colour.  Regrettably, this repre-
              sentation yields slide files which occupy more disc
              space and take longer to display.

       -background colour
              Most  AutoCAD  display drivers can be configured to
              use any available colour as the screen  background.
              Some users perfer a black screen background, others
              white, while splinter groups advocate burnt  ocher,
              tawny  puce,  and shocking grey.  Discarding pixels
              whose  closest  AutoCAD  colour  representation  is
              equal  to  the  background colour can substantially
              reduce the size of the AutoCAD  database  or  slide
              file  needed  to  represent a bitmap.  If no -back-
              ground colour is specified, the  screen  background
              colour  is assumed to be black.  Any AutoCAD colour
              number may be specified as the  screen  background;
              colour  numbers  are  assumed  to  specify the hues
              defined in the standard AutoCAD 256 colour 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 -back-
              ground 7.

       -aspect ratio
              If the source pixmap  had  non-square  pixels,  the
              ratio  of the pixel width to pixel height should be
              specified as ratio.  The resulting  slide  or  .dxb
              file  will be corrected so that pixels on the Auto-
              CAD screen will be square.  For example, to correct
              an  image made for a 320x200 VGA/MCGA screen, spec-
              ify -aspect 0.8333.

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

       All flags can be abbreviated to their shortest unique pre-
       fix.

BUGS
       AutoCAD has a fixed palette of  256  colours,  distributed
       along  the  hue,  lightness, and saturation axes.  Pixmaps
       which contain many nearly-identical  colours,  or  colours
       not  closely  approximated  by  AutoCAD's  palette, may be
       poorly rendered.

       ppmtoacad works best if the system displaying  its  output
       supports the full 256 colour AutoCAD palette.  Monochrome,
       8 colour, and 16 colour 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 colour
       but it's no substitute for true raster to  vector  conver-
       sion.   In  particular,  thin diagonal lines are not opti-
       mised at all by this process.

       Output files can be huge.

SEE ALSO
       AutoCAD Reference Manual: Slide  File  Format  and  Binary
       Drawing Interchange (DXB) Files, ppm(5)

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 soft-
       ware 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.

                         10 October 1991                        1