Furthermore, the integration of PS2Wide patches into (Open PS2 Loader) means you don't even need to patch your ISO files anymore. You simply place a .pnach file in a folder, and OPL applies the widescreen hack on-the-fly.
Essentially, the patch tells the game engine: "Zoom the camera out horizontally to capture 33% more of the world, but keep the vertical height the same." ps2wide