A battery-operated portable electronic device has a primary battery to provide energy to low current circuitry of the portable device, and a supplemental battery to provide intermittent bursts of energy to other components of the portable device. The method includes forming a cover on each bucket radial tip wherein the cover includes a leading edge side in a direction of rotation, and a trailing edge side in the direction of rotation wherein the leading edge and trailing edges are parallel with respect to each other, and wherein the leading edge and trailing edges are skewed with respect to the axis of rotation. The method also includes encoding the window of pixel values with a value determined from pixel values within the window and the number of pixel values within the window. Other embodiments are also described and claimed. The signal includes a variable component that has discernable properties in a frequency domain. The stereoscopic image display includes a data driving circuit that supplies a data voltage to data lines of a display panel; a gate driving circuit that supplies a gate pulse to gate lines of the display panel; and a timing controller that controls operation timings of the data driving circuit and gate driving circuit.