Some "highly compressed" releases (specifically for PS2) will re-encode FMV (Full Motion Videos) from 30fps to 15fps or reduce the resolution from 640x480 to 320x240. The gameplay remains intact, but cutscenes look like YouTube from 2007.
Many developers filled the outer edge of discs with garbage data (null bytes) to push game data to the faster-reading inner rings of the disc. Compressors strip this out. This is 100% lossless. Tools like UltraISO or CDMage allow this without touching gameplay. pes ps2 highly compressed
Since PS2 discs are obsolete, you need software that mimics the console hardware. pes ps2 highly compressed