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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 3.3//EN">
<html><head><title>Pgmramp User Manual</title></head>
<body>
<h1>pgmramp</h1>
Updated: 15 February 2014
<br>
<a href="#index">Table Of Contents</a>
<h2>NAME</h2>
pgmramp - generate a grayscale ramp
<h2 id="synopsis">SYNOPSIS</h2>
<b>pgmramp</b>
{<b>-lr</b>|<b>-tb</b>|<b>-rectangle</b>|<b>-ellipse</b>|<b>-diagonal</b>}
[<b>-maxval=</b><i>maxval</i>]
<i>width</i> <i>height</i>
<p>All options can be abbreviated to their shortest unique prefix.
You may use two hyphens instead of one to designate an option. You
may use either white space or an equals sign between an option name
and its value.
<h2 id="description">DESCRIPTION</h2>
<p>This program is part of <a href="index.html">Netpbm</a>.
<p>Generates a graymap of the specified size containing a
black-to-white ramp. These ramps are useful for multiplying with
other images, using <b>pamarith</b>.
<p>The ramp is linear in brightness, not intensity. I.e. the
gamma-corrected sample values in the PGM rise linearly with distance
from the corner of the image. If you want a ramp that is linear in
light intensity, use <b>pnmgamma</b> with <b>pgmramp</b>.
<p>Options let you choose the shape of the ramp (left to right, inside
out, etc.). You can use <b>pamflip</b> to get more shapes. For
example, the <b>-lr</b> option gives you a left to right ramp and
<pre>
<kbd>
$ pgmramp -lr 100 100 | pamflip -lr
</kbd>
</pre>
gives you a right to left ramp.
<p>To generate a simple ramp of all the values from 0 to maxval, and not
necessarily a graphic image, use <b><a href="pamseq.html">pamseq</a></b>.
<p><b>ppmrainbow</b> does something similar to what <b>pgmramp</b> does,
but for color. The image fades between two colors of your choice.
<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>pgmramp</b> recognizes the following
command line options:
<p>
You must specify exactly one of the ramp type options.
<dl compact>
<dt><b>-lr</b>
<dd>
A left to right ramp. Black on the left; white on the right.
<dt><b>-tb</b>
<dd>
A top to bottom ramp. Black on top; white on the bottom.
<dt><b>-rectangle</b>
<dd>
An outside-in rectangular ramp. It is black around the edges and white
in the center.
<dt><b>-ellipse</b>
<dd>
An outside-in elliptical ramp. It is black around the edge and white
in the center.
<dt><b>-diagonal</b>
<dd>
A ramp from top left corner diagonally down to bottom right. Black at
the top left; white at the bottom right.
<p>
This option was new in Netpbm 10.66 (March 2014).
<dt><b>-maxval=</b><i>maxval</i>
<dd>
The maxval for the generated image. Default is 255.
<p>
This option was new in Netpbm 10.1 (June 2002). Before that, the maxval
is always 255.
</dl>
<h2 id="seealso">SEE ALSO</h2>
<a href="pamflip.html"><b>pamflip</b></a>,
<a href="pamarith.html"><b>pamarith</b></a>,
<a href="pnmgamma.html"><b>pnmgamma</b></a>,
<a href="pamseq.html"><b>pamseq</b></a>,
<a href="ppmrainbow.html"><b>ppmrainbow</b></a>,
<a href="pamgradient.html"><b>pamgradient</b></a>,
<a href="pgm.html">pgm</a>
<h2 id="author">AUTHOR</h2>
Copyright (C) 1989 by Jef Poskanzer.
<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="#seealso">SEE ALSO</a>
<li><a href="#author">AUTHOR</a>
</ul>
</body>
</html>
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