According to one embodiment, a system includes a handheld device having a pixelated sensor, an optical filter for passing a predetermined frequency band of radiation to the sensor and a transmitter, an electronic equipment having a display, and at least two spaced-apart markers, where each of which are positioned proximate to the display. The markers provide radiation at the frequency band passed by the optical filter. The handheld device includes a processor coupled to receive image data of the markers from the sensor for computing coordinate data from the image data. The coordinate data requires less data than the image data. The processor is coupled to the transmitter to transmit the coordinate data to the electronic equipment. Other methods and apparatuses are also described.