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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
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<title>Pamtooctaveimg User Manual</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<body>
<h1>pamtooctaveimg</h1>
<p>Updated: 27 June 2007<br />
<a href="#index">Table Of Contents</a></p>
<h2>NAME</h2>
<p>pamtooctaveimg - convert a Netpbm image to a GNU Octave image</p>
<h2 id="synopsis">SYNOPSIS</h2>
<p><b>pamtooctaveimg</b>
[<i>netpbmfile</i>]
<h2 id="description">DESCRIPTION</h2>
<p>This program is part of <a href="index.html">Netpbm</a>.</p>
<p><b>pamtooctaveimg</b> reads a Netpbm image as input and produces a <a
href="http://www.octave.org/">GNU Octave</a> image file as output.
<p>An Octave image file (called "Octave's image format" in
Octave documentation) is a particular kind of Octave data file. It
describes two matrices:
<ol>
<li>the image itself as a list of indexes into a colormap, and</li>
<li>the corresponding colormap as a list of {red, green, blue} triplets.</li>
</ol>
<p>An Octave data file is an ASCII text file that you use to import data
to Octave.
<p>See the <a
href="http://www.gnu.org/software/octave/doc/interpreter/Image-Processing.html#Image-Processing">
Image Processing chapter</a> of the GNU Octave manual for details.
<h2 id="arguments">Arguments</h2>
<p><i>netpbmfile</i> is the name of the file containing the input PNM
or PAM image, or <b>-</b> to indicate Standard Input. If you don't
specify <i>netpbmfile</i>, the input is from Standard Input.
<b>pamtooctaveimg</b> converts only the first image in the input stream.
<b>pamtooctaveimg</b> writes the output Octave image to Standard Output.
<h2 id="examples">Examples</h2>
<p>
<pre>
<kbd>
% pamtooctaveimg myimage.ppm > myimage.img
% octave
> [img,map] = loadimage("myimage.img");
# (At this point, img is an X by Y matrix and map is a 3 by M matrix.)
> imshow(img,map); # Displays img with colormap map
> [r,g,b] = ind2rgb(img,map);
# (r, g, and b are now each X by Y matrices of color levels [0 to 1].)
> [newimg,newmap] = rgb2ind(r,b,g); # Swap the blue and green channels.
> saveimage("newimage.ppm", newimg, "ppm", newmap); # Save as a PPM file.
</kbd>
</pre>
<h2 id="notes">NOTES</h2>
<p>There is no <b>octavetopam</b> program. However, GNU Octave's
<b>saveimage</b> command can save images in PPM format.</p>
<h2 id="history">HISTORY</h2>
<p><b>pamtooctaveimg</b> was new in Netpbm 10.39 (June 2007).
<h2 id="seealso">SEE ALSO</h2>
<a
href="http://www.gnu.org/software/octave/doc/interpreter/index.html"><b>octave</b></a>,
<a href="pam.html"><b>pam</b></a>.</p>
<h2><a id="author">AUTHOR</a></h2>
<p>Copyright (C) 2007 Scott Pakin,
<a href="mailto:scott+pbm@pakin.org">scott+pbm@pakin.org</a>.</p>
<hr />
<h2 id="index">Table Of Contents</h2>
<ul>
<li><a href="#synopsis">SYNOPSIS</a></li>
<li><a href="#description">DESCRIPTION</a></li>
<li><a href="#arguments">ARGUMENTS</a></li>
<li><a href="#examples">EXAMPLES</a></li>
<li><a href="#notes">NOTES</a></li>
<li><a href="#history">HISTORY</a></li>
<li><a href="#seealso">SEE ALSO</a></li>
<li><a href="#author">AUTHOR</a></li>
</ul>
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