This is achieved by repacking data, removing dummy files (used to push data to the outer edge of a disc for faster reading), and using formats like with maximum compression.
: PCSX2 can load games directly from GZIP archives, building an index for fast access.
Widely reviewed as the "best" format because it is lossless (no content is removed) and can be read directly by many modern emulators like PCSX2 and AetherSX2 .
Compressed ISO formats originally popularized for the PSP but sometimes used in PS2 homebrew circles. Game Rips: