ale/doc/user/eppm/index.xml

<?xml version="1.0"?>

<!DOCTYPE book PUBLIC "-//Norman Walsh//DTD DocBk XML V3.1.4//EN"
	"file:///usr/share/xml/docbook/schema/dtd/4.4/docbookx.dtd">

<chapter id="user-eppm"><title>Extended PPM (EPPM) Files</title>

<p>EPPM is an extension to the PPM file format that allows specification of
metadata.  The header of an EPPM file conforms to the following template:</p>

<pre>P6#E
# Tag1: Value
# Tag2: Value
# Tag3: Value
# .
# .
# .
Width Height Maxval
Data
</pre>

<p>Tags recognized by ALE are outlined below.</p>

<s><t>Black level</t>

<p>The black level tag specifies a value that should be subtracted from
all pixels in order to achieve linearity.  A modified version of dcraw (<a
href="/darcs/dcraw">darcs repository</a>) can be used to generate files
containing this tag.</p>

<pre># Black-level: &lt;value&gt;
</pre>

</s><s><t>Exposure tags</t>

<p>Exposure tags can be used for determining tonal registration through
specification of shutter speed, aperture, and ISO sensitivity (or gain).</p>

<pre># Shutter: &lt;value&gt;
# Shutter: 1/&lt;value&gt;
# Aperture: &lt;f-number&gt;
# ISO: &lt;value&gt;
# Gain: &lt;value&gt;
</pre>

</s>


</chapter>