How to enable GD2 extension in PHP

Extension = php_gd2.dll

Find the PHP configuration file PHP. ini, search for extension = php_gd2.dll, and remove the semicolon;
If this is not directly added, it is applicable to the Windows system and PHP that supports GD during compilation. Just save it and restart Apache.
For example, Deb of ubuntu. Run the command to install PHP installed by RedHat RPM.
Ubuntu: sudo apt-Get install php5-gd
RedHat: Yum install PHP-Gd
FreeBSD can use the package of systeminstall to install GD2.
If it is compiled and installed and does not support GD, you need to install GD first, and then re-compile PHP