Admin/environment/php extension/gd
From Learnit docs
GD module for php5
This package provides a module for handling graphics directly from PHP scripts. It supports the PNG, JPEG, XPM formats as well as Freetype/ttf fonts.
Install GD module for php 5
Ubuntu: Download and install gd
sudo apt-get install php5-gd
You might need to restart Apache (not necessary)
sudo /etc/init.d/apache2 restart
Centos: Download and install gd
yum install php-gd
You might need to restart Apache (not necessary)
sudo /etc/init.d/apache2 restart
