A TimThumb error has occured

The following error(s) occured:

GD Library Error: imagecreatetruecolor does not exist - please contact your webhost and ask them to install the GD library

Query String : w=720&h=1280&src=http%3A%2F%2Fmoriartus.com%2Fwp-content%2Fuploads%2F2011%2F12%2FIMG_5878retina.jpg
TimThumb version : 2.8.14