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.