PHP Manual: Requirements

Requirements

If you have the GD library (available at » http://www.libgd.org/) you will also be able to create and manipulate images.

The format of images you are able to manipulate depend on the version of GD you install, and any other libraries GD might need to access those image formats. Versions of GD older than gd-1.6 support GIF format images, and do not support PNG, where versions greater than gd-1.6 and less than gd-2.0.28 support PNG, not GIF. GIF support was re-enabled in gd-2.0.28.

Note: Since PHP 4.3 there is a bundled version of the GD lib. This bundled version has some additional features like alpha blending, and should be used in preference to the external library since its codebase is better maintained and more stable.

You may wish to enhance GD to handle more image formats.

**Supported image formats**
Image format	Library to download	Notes
gif		Only supported in GD versions older than gd-1.6 and newer than gd-2.0.28. Read-only GIF support is available with PHP 4.3.0 and the bundled GD-library. Write support is available since PHP 4.3.9 and PHP 5.0.1.
jpeg	» http://www.ijg.org/	When building the jpeg library (prior to building PHP) you must use the --enable-shared option in the configure step. If you do not, you will receive an error saying libjpeg.(a\|so) not found when you get to the configure step of building PHP.
png	» http://www.libpng.org/pub/png/libpng.html	Only supported in GD versions greater than gd-1.6.
xpm	» ftp://metalab.unc.edu/pub/Linux/libs/X/!INDEX.html	It's likely you have this library already available, if your system has an installed X-Environment.

You may wish to enhance GD to deal with different fonts. The following font libraries are supported:

**Supported font libraries**
Font library	Download	Notes
FreeType 1.x	» http://www.freetype.org/	This deprecated feature will certainly be removed in the future.
FreeType 2	» http://www.freetype.org/
T1lib	» ftp://sunsite.unc.edu/pub/Linux/libs/graphics/)	Support for Postscript Type 1 fonts.