BTI file

BTI is an image file format similar to TEX0, TPL and BREFT file formats. The only difference is the file header.

File Format

The file format is very simple and starts with a file header followed by the image data. All data is written in big endian.

File Header

The following table shows the file header. It is 0x20 bytes long. There is no magic to identify BTI files, so tools may do some plausibility checks to identify them.

File Header

Offset	Type	Description
0x00	Byte	Image format.
0x01	Byte	Enable alpha (0x00 means alpha is disabled, anything higher means alpha is enabled).
0x02	UInt16	Width of the image in pixels.
0x04	UInt16	Height of the image in pixels.
0x06	Byte	Wrap S[1] (0x01 for posteffect.bti, 0x00 for others). Probably repeat, clamp or mirror wraps for U projection maps.
0x07	Byte	Wrap T[2] (0x01 for posteffect.bti, 0x00 for others). Probably repeat, clamp or mirror wraps for V projection maps.
0x08	UInt16	Palette format (not used in Mario Kart Wii).
0x0A	UInt16	Number of palette entries.
0x0C	UInt32	Offset to palette data, relative to the start of the file header.
0x10	UInt32	Template:Unknown-left Always 0 in Mario Kart Wii.
0x14	Byte	Magnification filter type (0x00 means nearest, 0x01 means linear).
0x15	Byte	Minification filter type.
0x16	UInt16	Template:Unknown-left Always 0 in Mario Kart Wii.
0x18	Byte	Total number of images, thus number of mipmaps + 1.
0x19	Byte	Template:Unknown-left Always 0 in Mario Kart Wii.
0x1A	UInt16	Template:Unknown-left Always 0 in Mario Kart Wii.
0x1C	UInt32	Offset to image data, relative to the start of the file header.
0x20	colspan=2 End of file header[unsure]

Image and Palette Data

The image and palette data starts at the given data offset in the file header. The data depends on the image and palette formats format. The image format values are listed below.

Credits: Gamecubing8619,Vulcan,wiki.tockdom.com