ppmtoacad(1)            UNIX System V(10 October 1991)             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(Reg.) 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 resulting


10/89                                                                    Page 1

ppmtoacad(1)            UNIX System V(10 October 1991)             ppmtoacad(1)


            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 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.

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.







Page 2                                                                    10/89