 After Luigi encounters a group of Boos hiding in the mansion, the device can be used to find each one hiding in a room, through a beeper sound and a flashing yellow light on the device, which turns red when Luigi is close to one; Boos can only be located in rooms that have become lit after their ghosts have been cleared out.Boos are trickier to deal with, as they can plant decoys and traps within objects they can hide in that can fool the Horror, and will escape into other rooms if they can, forcing the player to chase after them.Once a stage is completed, all portrait ghosts are restored to their paintings by E. Gadd, which the player can view in his laboratory's gallery, at which point a result screen reveals the portrait ghosts Luigi has managed to capture, along with the total amount of treasure he recovered for that stage.