US Patent 8035624 Computer vision based touch screen

A self-contained interactive video display system. A projector projects a visual image onto a screen for displaying the visual image, wherein the projector projects the visual image onto a back side of the screen for presentation to a user on a front side of the screen. An illuminator illuminates an object near the front side of the screen. A camera detects interaction of an illuminated object with the visual image, wherein the screen is at least partially transparent to light detectable to the camera, allowing the camera to detect the illuminated object through the screen. A computer system directs the projector to change the visual image in response to the interaction.