ppmtoacad(1) General Commands Manual ppmtoacad(1)
ppmtoacad - convert portable pixmap to AutoCAD database or slide
ppmtoacad [-dxb] [-poly] [-background colour] [-white] [-aspect ratio] [-8] [ppmfile]
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.
-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
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.
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.
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
Output files can be huge.
AutoCAD Reference Manual: Slide File Format and Binary Drawing Interchange (DXB) Files, ppm(5)
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10 October 1991 ppmtoacad(1)