Installation instructions updated, missing dependency

I followed the instructions and didn't work for me on Ubuntu 12.04 without ImageMagick.

I found the missing dependency in this forum:

http://forum.ubuntu.ru/index.php?PHPSESSID=guerkhun86jofh17v4i4c2elb4&topic=203120.msg1780687#msg1780687

Thanks for the driver, great work ;-)

Regards,
David.