Dolphin sorts custom textures using the game's unique Game ID. The ID depends on your game's region: SEME01 Europe (PAL): SEMP01 Japan (NTSC-J): SEMJ01
In simple terms, an HD Texture Pack is a collection of replacement image files. Emulators like Dolphin allow you to dump the original textures from a game, edit them in Photoshop (or similar software), and then load those high-resolution versions instead of the originals. rhythm heaven fever hd texture pack