This makes it possible to show existing video content that has been “upscaled” for Ultra HD without the need for black “letterbox” bands above and below the picture.
Two alcoves facing each other were meant to hold oil lamps and personal belongings, and Singh explained that the small, square-shaped hollow near the entrance of the cell served as each student's personal letterbox.
Between the overhang of the roof and the tops of the eucalyptus trees, he has only a letterbox view of the sky, but he says it was more than good enough for his purposes.