Abstract: A portable display device is operative to modulate the appearance of a real or virtual image in response to the motion of the display device with respect to its relative movement with respect the object's virtual position. The display in effect becomes a portable window into a virtual world. The virtual object can be created from a real object by image capture and can be 2 or 3 dimensional. Specific modes of display movement can be used to infer a relative movement of the display window with respect to the one or more objects in the virtual world.