Get Image Gallery #1:
Scan 50% of the Creature & research data

Get art gallery 2:
Scan 100% everything

Get Image Gallery #3:
Collect 100% all items

Get Image Gallery #4:
Finish the game on Hard mode

Cinema Metroidiso:
Collect every Missile expansion, power bomb expansion, and Energy tank in the game and you'll unlock a secret end of the game cinema.