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ppmtoacad(1)                         General Commands Manual                         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 output.  If no ppmfile is specified, input is read from standard in-
       put.

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  geometrical  data-
              base  and can be viewed and edited like any other object.  Each sequence of identi-
              cal 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 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 rendered 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 representation yields slide files which oc-
              cupy 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.   Dis-
              carding  pixels  whose  closest AutoCAD colour representation is equal to the back-
              ground colour can substantially reduce the size of the AutoCAD  database  or  slide
              file  needed  to  represent  a  bitmap.  If no -background 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 -background 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 cor-
              rected  so  that pixels on the AutoCAD screen will be square.  For example, to cor-
              rect an image made for a 320x200 VGA/MCGA screen, specify -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 prefix.

BUGS
       AutoCAD has a fixed palette of 256 colours, distributed along the hue, lightness, and sat-
       uration 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  Au-
       toCAD  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 ver-
       tical  and  horizontal runs of identical pixels and consolidates them into rectangular re-
       gions to reduce the size of the output file.  This is effective for images with large  ar-
       eas  of  constant  colour but it's no substitute for true raster to vector conversion.  In
       particular, thin diagonal lines are not optimised 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 AT 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.

                                         10 October 1991                             ppmtoacad(1)

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