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 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 geometrical database and can be viewed and edited 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  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.  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 -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 result-
	      ing slide or .dxb file will be corrected 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 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 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  con-
       stant  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@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)