In the context of Rockstar Games' RenderWare engine (used in GTA 3, Vice City, and San Andreas), the file is the archive located in GTA III/models/ . It contains almost all the game’s visual assets, including:
The most reputable sources for mods are GTAInside.com, NexusMods.com, and LibertyCity.net. Look for mods tagged as "HD," "high quality," "texture pack," or "remaster." Some notable examples include: gta3 img file extra quality
Are you running the or the The Definitive Edition ? In the context of Rockstar Games' RenderWare engine