They use the GD library.

它们使用gd库。

GD has a nice looking user interface and it's very easy to use.

广东有一个很好看的用户界面和它的非常容易使用。

GD is included with PHP 4.3 and higher and usually enabled by default.

PHP 4.3以上版本通常包括GD库，默认情况下一般已经启用。

Download and install the GD module from your favorite CPAN mirror.

从您最喜欢的cpan镜像下载并安装GD模块。

Notice that you don't need to specify the gd: prefix for the element tag.

注意，无需为element标记指定gd：前缀。