Berlin
We provide on our requirements page a phpinfo script to verify your server has all the requirements to install this product before you buy the script.
You must have GD or Imagemagick to operate any gallery program as that is the actual image processor.
If you are attempting to install the script and do not have mogrify installed on the server (imagemagick) your php must have gd installed with it. You would select GD instead of Imagemagick.
If your server has neither one and no SSH access. You host would need to compile imagemagick on the server for you or recompile php with Gd support. If you have SSH access but only to your part of the server you may be able to install a non-root install of Imagemagick
All the info you need to do these things is right on this site.
http://www.photopost.com/magicknoroot-php.html