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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 3.3//EN">
<html><head><title>Sgitopnm User Manual</title></head>
<body>
<h1>sgitopnm</h1>
Updated: 25 April 2014
<br>
<a href="#index">Table Of Contents</a>
<h2>NAME</h2>
sgitopnm - convert a SGI image file to PNM
<h2 id="synopsis">SYNOPSIS</h2>
<b>sgitopnm</b>
[<b>-verbose</b>]
[<b>-channel</b> <i>c</i>]
[<i>SgiFileName</i>]
<h2 id="description">DESCRIPTION</h2>
<p>This program is part of <a href="index.html">Netpbm</a>.
<p><b>sgitopnm</b> reads an SGI image file as input and produces a PGM
image for a 2-dimensional (1- or 2-channel) input file, and a PPM image for
a 3-dimensional (3 or more channels) input file.
<p>Alternatively, the program produces a PGM image of any one of the
channels in the input file.
<p>Before Netpbm 10.67 (June 2014), <b>sgitopnm</b> does not work on 2-channel
SGI images. It fails if you try.
<p>If you don't specify the <i>SgiFileName</i> argument, input is from
Standard Input.
<p>Before Netpbm 10.67 (June 2014), <b>sgitopnm</b> requires its input to
be a seekable file, so for example you can't feed it from a pipe.
<h2 id="options">OPTIONS</h2>
<p>In addition to the options common to all programs based on libnetpbm
(most notably <b>-quiet</b>, see <a href="index.html#commonoptions">
Common Options</a>), <b>sgitopnm</b> recognizes the following
command line options:
<dl compact>
<dt><b>-verbose</b>
<dd>Give some information about the SGI image file.
<dt><b>-channel</b> <i>n</i>
<dd>Extract channel <i>n</i> of the image as a PGM image.
<p>Without this option, <b>sgitopnm</b> extracts the first 3 channels as a PPM
image or, if the input has 1 or 2 channels, extracts the first channel as a
PGM image.
<p>A 2-channel image is grayscale plus transparency, so you can get
the transparency information with <b>-channel=2</b>. You could then
combine them into a PAM image of tuple type GRAYSCALE_ALPHA with
<b>pamstack</b>.
</dl>
<h2 id="references">REFERENCES</h2>
<p>The SGI image format specification version 1.0 is at
ftp://ftp.sgi.com/graphics/grafica/sgiimage.html .
<p>There is an example SGI file at
https://github.com/ZaaLabs/ZaaIL-TestImages/tree/master/SGI .
<h2 id="seealso">SEE ALSO</h2>
<b><a href="pnm.html">pnm</a></b>,
<b><a href="pam.html">pam</a></b>,
<b><a href="pnmtosgi.html">pnmtosgi</a></b>,
<b><a href="pamstack.html">pamstack</a></b>
<h2 id="author">AUTHOR</h2>
<p>Copyright (C) 1994 by Ingo Wilken
(<a href="mailto:Ingo.Wilken@informatik.uni-oldenburg.de">
Ingo.Wilken@informatik.uni-oldenburg.de</a>)
<hr>
<h2 id="index">Table Of Contents</h2>
<ul>
<li><a href="#synopsis">SYNOPSIS</a>
<li><a href="#description">DESCRIPTION</a>
<li><a href="#options">OPTIONS</a>
<li><a href="#references">REFERENCES</a>
<li><a href="#seealso">SEE ALSO</a>
<li><a href="#author">AUTHOR</a>
</ul>
</body>
</html>
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