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

       ppmtoacad - convert PPM to Autocad database or slide




       [-background color]


       [-aspect	ratio]



       This program is part of Netpbm(1).

       ppmtoacad  reads	 a PPM image as	input and produces an Autocad(R) 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).

       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	 iden-
	      tical 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 Au-
	      tocad 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 dis-
	      play 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	avail-
	      able  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 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 back-
	      ground 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

       -white Since  many Autocad users	choose a white screen background, this
	      option is	provided as a short-cut.  Specifying -white is identi-
	      cal 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.

       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  approxi-
       mated 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, ppm-
       toacad 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.

       Autocad Reference Manual: Slide File Format and Binary  Drawing	Inter-
       change (DXB) Files, ppm(5)

       John Walker
       Autodesk	SA
       Avenue des Champs-Montants 14b
       CH-2074 MARIN
	   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,	 with-
       out  any	conditions or restrictions.  This software is provided "as is"
       without express or implied warranty.

       Autocad and Autodesk are	registered trademarks of Autodesk, Inc.

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

netpbm documentation		10 October 1991	      Ppmtoacad	User Manual(0)


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