1. A mobile device comprising: an imager configured to provide a first depth image including a first foreground and a first original background and a subsequent second depth image including a second foreground and a second original background; a storage configured to store a substitute background; a sensor configured to sense movement of the mobile device; and a processor configured to: separate the first foreground from the first original background of the first depth image, replace the first original background with the substitute background to form a first composite image modulate the substitute background as a function of a movement of the mobile device sensed by the sensor to form a modulated substitute background, and replace the second original background with the modulated substitute background to form a second composite image.