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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 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).


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 com-
              mand 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 specify -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 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 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.  Discarding pixels whose closest Autocad color representation is equal to
              the  background  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 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.



RESTRICTIONS
       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 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 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 vec-
       tor 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:kelvinATAutodesk.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)