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Ppmtoacad User Manual(0)						 Ppmtoacad User Manual(0)

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(R) slide file or binary data-
       base 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 documenta-
       tion uses standard American typography, wherein that is not a valid  form  of  capitaliza-
       tion).

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 spec-
	      ify -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 pix-
	      els to expand instead of appearing as discrete lines against the screen  background
	      color.  Regrettably, this representation yields slide files which occupy more stor-
	      age 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.   Dis-
	      carding  pixels  whose  closest  Autocad color representation is equal to the back-
	      ground 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 cor-
	      rect  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, spec-
	      ify -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 satu-
       ration 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 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 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.

netpbm documentation			 10 October 1991		 Ppmtoacad User Manual(0)
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