1Ppmtoacad User Manual(0)                              Ppmtoacad User Manual(0)
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NAME

6       ppmtoacad - convert PPM to Autocad database or slide
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SYNOPSIS

10       ppmtoacad
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12       [-dxb]
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14       [-poly]
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16       [-background color]
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18       [-white]
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20       [-aspect ratio]
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22       [-8]
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24       [ppmfile]
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DESCRIPTION

29       This program is part of Netpbm(1).
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31       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.
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35       (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).
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OPTIONS

41       You may abbreviate any option to its shortest unique prefix.
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45       -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.
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55       -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.
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66       -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.
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81       -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.
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86       -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.
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95       -8     Restricts the colors in the output file to the 8 RGB shades.
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RESTRICTIONS

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.
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105       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.
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109       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.
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116       Output files can be huge.
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SEE ALSO

120       Autocad Reference Manual: Slide File Format and Binary  Drawing  Inter‐
121       change (DXB) Files, ppm(1)
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AUTHOR

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
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134       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.
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139       Autocad and Autodesk are registered trademarks of Autodesk, Inc.
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143netpbm documentation            10 October 1991       Ppmtoacad User Manual(0)
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