GD image format

GD image format is a raster graphics file format associated with the GD graphics library (a.k.a. LibGD), originally developed by Thomas Boutell.

The GD image format is a special purpose format that can be read very quickly. It is not GD's preferred format -- standard formats like GIF and PNG are preferred.

There are several versions of GD format.

See also GD2 image format.

Identification
GD 1.x: There's no easy way to identify this format version.

GD 2.x palette color: Starts with bytes, and has at offset 6.

GD 2.x truecolor: Starts with bytes (v2.0.0-2.0.11) or  (v2.0.12+), and has  at offset 6.

Specifications

 * Refer to the source code comments in modern versions of the gd_gd.c file.

Software

 * GD/LibGD
 * GD 1.2, from the Wayback Machine
 * https://ftp.mizar.org/packages/gd/ - Various versions
 * See the LibGD website for the latest release.
 * LibGD GitHub project

Links

 * LibGD website