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 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 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: [email protected]
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.
10 October 1991 ppmtoacad(1)
Opportunity
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
Free Books
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Education
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.
