1. A computing system comprising: a projection screen comprising; a first surface to specularly reflect infrared (IR) light, and a second surface to diffuse visible light; an IR camera disposed above and pointed at the projection screen to capture an IR image representing an object disposed between the IR camera and the projection screen based on an intensity of IR light reflected by the object and the projection screen; a segmentation engine to determine a segmentation boundary representing at least one outer edge of the object disposed between the IR camera and the projection screen based on the IR image, wherein the segmentation engine removes portions of the IR image outside the segmentation boundary to generate an image of the object; and a projector assembly to: project IR light on the projection screen; and project portions of the IR image that lie inside the segmentation boundary that correspond to the object disposed between the IR camera and the projection screen on the projection screen.