RAWTex

RAWTex is a save plugin for GIMP 2.2.x, 2.3.x & 2.4.x allowing to create raw textures for the PC, PSP, NDS, PS2 or any other architecture handling chunky or compressed dxtc formats.

It can save raw RGBA (5650, 5551, 4444 or 8888) & indexed (T4, T8) textures (with 5650, 5551, 4444 or 8888 palette modes support) as well as DXTC (DXT1, DXT3, DXT5) compresssed ones, it supports the PSP textures swizzle mode and can generate mipmaps, it also have a color key feature to handle transparency and can convert grayscale pictures into alpha channel only textures.