1Ppmtoacad User Manual(0) Ppmtoacad User Manual(0)
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6 ppmtoacad - convert PPM to Autocad database or slide
7
10 ppmtoacad
11 [-dxb]
13 [-poly]
15 [-background color]
17 [-white]
19 [-aspect ratio]
21 [-8]
23 [ppmfile]
25
29 This program is part of Netpbm(1).
30 ppmtoacad reads a PPM image as input and produces an Autocad® slide
32 file or binary database import (.dxb) file as output. If you don't
33 specify ppmfile, ppmtoacad takes the input from Standard Input.
34 (Typographical note: the name of Autocad is often rendered as AutoCAD.
36 Netpbm documentation uses standard American typography, wherein that is
37 not a valid form of capitalization).
38
41 You may abbreviate any option to its shortest unique prefix.
42 -dxb ppmtoacad writes an Autocad binary database import (.dxb) file.
46 You read this file with the DXBIN command and, once loaded, it
47 becomes part of the Autocad geometrical database, so you can
48 view and edit it like any other object. Each sequence of iden‐
49 tical pixels becomes a separate object in the database; this can
50 result in very large Autocad drawing files. However, if you
51 want to trace over a bitmap, it lets you zoom and pan around the
52 bitmap as you wish.
53 -poly If you don't specify the -dxb option, ppmtoacad generates an
56 Autocad slide file. Normally each row of pixels is represented
57 by an Autocad line entity. If you specify -poly, ppmtoacad ren‐
58 ders the pixels as filled polygons. If you view the slide on a
59 display with higher resolution than the source image, this will
60 cause the pixels to expand instead of appearing as discrete
61 lines against the screen background color. Regrettably, this
62 representation yields slide files which occupy more storage
63 space and take longer to display.
64 -background color
67 Most Autocad display drivers can be configured to use any avail‐
68 able color as the screen background. Some users prefer a black
69 screen background, others white, while splinter groups advocate
70 burnt ocher, tawny puce, and shocking gray. Discarding pixels
71 whose closest Autocad color representation is equal to the back‐
72 ground color can substantially reduce the size of the Autocad
73 database or slide file needed to represent a bitmap. If you
74 don't specify -background, ppmtoacad assumes the screen back‐
75 ground color to be black. You may specify any Autocad color
76 number as the screen background; ppmtoacad assumes color numbers
77 to specify the hues defined in the standard Autocad 256 color
78 palette.
79 -white Since many Autocad users choose a white screen background, this
82 option is provided as a short-cut. Specifying -white is identi‐
83 cal in effect to -background 7.
84 -aspect ratio
87 If the source image had non-square pixels (which means it is not
88 standard PPM), specify the ratio of the pixel width to pixel
89 height as ratio. ppmtoacad will correct the resulting slide or
90 .dxb file so that pixels on the Autocad screen will be square.
91 For example, to correct an image made for a 320x200 VGA/MCGA
92 screen, specify -aspect 0.8333.
93 -8 Restricts the colors in the output file to the 8 RGB shades.
96
100 Autocad has a fixed palette of 256 colors, distributed along the hue,
101 lightness, and saturation axes. So it may poorly render images which
102 contain many nearly-identical colors, or colors not closely approxi‐
103 mated by Autocad's palette.
104 ppmtoacad works best if the system displaying its output can display
106 the full 256 color Autocad palette. Monochrome, 8 color, and 16 color
107 configurations will produce less than optimal results.
108 When creating a .dxb file or a slide file with the -poly option, ppm‐
110 toacad finds both vertical and horizontal runs of identical pixels and
111 consolidates them into rectangular regions to reduce the size of the
112 output file. This is effective for images with large areas of constant
113 color but it's no substitute for true raster to vector conversion. In
114 particular, this process does not optimize thin diagonal lines at all.
115 Output files can be huge.
117
120 Autocad Reference Manual: Slide File Format and Binary Drawing Inter‐
121 change (DXB) Files, ppm(1)
122
125 John Walker
126 Autodesk SA
127 Avenue des Champs-Montants 14b
128 CH-2074 MARIN
129 Suisse/Schweiz/Svizzera/Svizra/Switzerland
130 Usenet:kelvin@Autodesk.com
131 Fax:038/33 88 15
132 Voice:038/33 76 33
133 Permission to use, copy, modify, and distribute this software and its
135 documentation for any purpose and without fee is hereby granted, with‐
136 out any conditions or restrictions. This software is provided 'as is'
137 without express or implied warranty.
138 Autocad and Autodesk are registered trademarks of Autodesk, Inc.
140netpbm documentation 10 October 1991 Ppmtoacad User Manual(0)