Not per file, per block of 16 pixels. They are transferred quite often - BCn is a texture compression scheme for realtime use in GPUs. Those textures are stored

Not per file, per block of 16 pixels. They are transferred quite often - BCn is a texture compression scheme for realtime use in GPUs. Those textures are stored and processed in compressed form. https://en.wikipedia.org/wiki/S3_Texture_Compression https://en.wikipedia.org/wiki/S3_Texture_Compression