Plugin for automatic generation of thumbnails

Hi all. I’ve written a plugin to automatically insert thumbnails with captions into a blog post. It’s my first attempt at PHP and is really little more than an ugly hack but I thought I might as well share it.
It’s reatively simple to use:
enter

<thumb>image.jpg?cap=Caption here<thumb>

and it will automatically generate the thumbnail and all the code necessary to insert it and its caption into your post.
Any comments or suggestions that anyone has are more than welcome.
You can get it, and more details, at my website:
https://www.ali-hassan.net