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ppmtoacad(1)									     ppmtoacad(1)

       ppmtoacad - convert portable pixmap to AutoCAD database or slide

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

       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

       -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
	      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.   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.

       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
       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 ver-
       tical  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 conversion.  In
       particular, thin diagonal lines are not optimised at all by this process.

       Output files can be huge.

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

	    John Walker
	    Autodesk SA
	    Avenue des Champs-Montants 14b
	    CH-2074 MARIN
	    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.

					 10 October 1991			     ppmtoacad(1)
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