Abstract: Presentation of composited video images onto a digital user interface enables an actor to move independently of the underlying application windows, increasing the dramatic effect and allowing accompanying digital content to be displayed in a complementary fashion. Chroma-key operation on the frames of the video image to detect a foreground portion of each frame provides a robust response to nonuniform background colors or to artifacts introduced during compression and transmission by threshold comparison of a variation of pixels in the frame to an expected or detected background color value.