Pmd2 BGP

The BGP file format is used in Pokémon Mystery Dungeon: Explorers of Time/Darkness/Sky to store full-screen background images, most notably the various images that appear in the background of the main menu.

It is stored using AT4PX compression.

Overview

Offset	Length	Name	Description
0x0	20	Header	Currently unresearched
0x20	1024	Palette	Stores 64 colors for use by the tiles.
0x420	620	Tile Mapping	For each 8x8 region of the screen, identifies which tile, palette, and transform to use.
0xC40	Unknown/Varies	Tiles	Consecutive 8x8 4bbp tiles for use in the tile mapping.

Palette

The palette consists of 1024 bytes, representing 256 colors. Each color has 4 bytes: Red, Green, Blue, and a 4th unknown byte which is always set to 0x80.