GXT

Standard test image widely used

GXT is a file format (used on PS Vita and PSP) for storing textures. The purpose of this format is to use it in the runtime without any additional formatting of the data.

Features

• Memory ready format
• Supports multiple textures in one file
• Supports compressed, swizzled, and linear texture layouts
• Supports mipmaps
• Suports palettized textures

File format

The GXT (.gxt) format consists of:

File Layout
GXT Header
GXT Specification Texture 1 info
GXT Specification Texture 2 info
...
Texture 1
Padding
Texture 2
...
Palette P4
Palette P8

• For a single texture:

Offset (h)	Size (h)	Example (h)	Value (conversion)	Notes
GXT header
0x00	0x04	47 58 54 00	"GXT "	Magic
0x04	0x04	03 00 00 10	3.01	Version
0x08	0x04	01 00 00 00	1	Number of textures embedded
0x0C	0x04	40 00 00 00	40	Offset of the texture data/ header size
0x10	0x04	80 00 00 00	80	Total size of the Textures
0x14	0x04	00 00 00 00	0	Number of 16 entry palettes (P4)
0x18	0x04	00 00 00 00	0	Number of 256 entry palettes (P8)
0x1C	0x04	00 00 00 00	0	Padding
GXT specification per texture
0x20	0x04	40 00 00 00	40	Offset of the single texture data
0x24	0x04	80 00 00 00	80	Size of the single texture data.
0x28	0x04	FF FF FF FF	-	Index of the palette
0x2C	0x04	00 00 00 00	-	Texture flags/Not used?
0x30	0x04	00 00 00 00	-	Texture Type
0x34	0x04	-	-	Texture format
0x38	0x02	-	-	Width
0x3A	0x02	-	-	Height
0x3C	0x02	-	-	Mipmaps
0x3E	0x02	-	-	Not Used?/Padding