If You are insatlling the 1.x branch then make sure the PHP version
used is at least 4.3.x (preferable 4.3.10 or higher) and that the PHP
version have compiled support for GD library. It is absolutely critical
that GD is fully working. Please see the earlier sections on how to
make sure. JpGraph supports both GD 1.x and GD 2.x However it is
strongly recommended to use GD 2.x since that will improve performance
and support true color images as well as alphablending.
If You are insatlling the 2.x branch then make sure the PHP version
used is at least 5.0.1 (preferable 5.0.5 or higher) and that the PHP
version have compiled support for GD 2.x library. Please note that the
2.x branch will not work with PHP 4.x