 In the IMAX presentation, four scenes (totalling about 20 minutes) were  converted from 2D to 3D: The flashback to Clark Kents youth on the farm, the  Shuttle/777 rescue, the rescue of the sinking ocean liner, and the final  flyover before the credits. Bryan Singer developed a cue featuring an icon of  Clarks glasses flashing in green at the bottom of the screen when it is time  to put them on, and then with a red circle/slash over when it is time to take  them off.