1. A method comprising: capturing an image of a shape projected upon a display surface; and using a processor to generate a rectangular bounding box containing the shape and determine a first rectangle that is the largest inscribed rectangle for the shape in the captured image by dividing the rectangular bounding box vertically into first and second sections, determining a second rectangle that is the largest inscribed rectangle for the shape in the first section of the bounding box, determining a third rectangle that is the largest inscribed rectangle for the shape in the second section of the bounding box, dividing the rectangular bounding box horizontally into third and fourth sections, determining a fourth rectangle that is the largest inscribed rectangle for the shape in a third section of the bounding box, determining a fifth rectangle that is the largest inscribed rectangle for the shape in the fourth section of the bounding box, selecting a top edge, and a bottom edge, of the first rectangle based on the second and third rectangles; and selecting a left edge, and a right edge, of the first rectangle based on the fourth and fifth rectangles.