Create a thumbnail from only part of an image
<p>I'm creating a thumbnail right now like this:</p>

<pre><code>// create thumbnail and save
var image = Image.FromFile(Server.MapPath(imageFilename));
var thumb = image.GetThumbnailImage(image.Width / 10, image.Height / 10, () =&gt; false, IntPtr.Zero);
thumb.Save(Server.MapPath(Path.ChangeExtension(imageFilename, "thumb" + Path.GetExtension(imageFilename))));
</code></pre>

<p>All it does is take the image, create a thumbnail 1/10th of the size, and save it.</p>

<p>I'd like to be able to create a thumbnail out of only part of the image. So say I have an image that is 200px by 200px. How can I take a 100px by 100px crop out of the middle of the image, and create a thumbnail out of it?</p>
