“Slightly compressed” is heavily used in 3D graphics -- see ETC2, DXT, etc. It’s useful because the size savings apply in memory, because decompression is so

“Slightly compressed” is heavily used in 3D graphics -- see ETC2, DXT, etc. It’s useful because the size savings apply in memory, because decompression is so cheap it can be done on the fly. It has to be lossy because you want a guaranteed fixed-rate compression ratio (eg 4x) and there’s no way to do that losslessly.