ImageAuth hack (using ImageMagick)

I’ve put together an ImageAuth hack for posting comments on your WordPress site. There is currently a hack that already does this but only supports GDlib. This version uses ImageMagick, and is offered as an alternative where GDlib is not available (Yet another tool in the WP toolbox!).
You can get it from http://www.wellardsworld.com/content/wphacks#imageauth
The hack can be seen working on my site at http://www.wellardsworld.com