A W6 engine has two W3 engine units disposed juxtaposed on a common crankshaft. The apparatus provides at least one light source that emits a light signal at a discrete frequency and a reference signal at the discrete frequency. The inverse mask image is generated based upon the color data for a selected one of the first set of colors so that the inverse mask pattern can be generated without first determining of color separation toner images that define amounts of color toner to be applied to a receiver to form the image. A biaserase coil located about the magneto-optic sensor can enhance or erase images on the sensor. On the other hand, when the macroblock to be processed is subjected to field-based encoding, a field-based context model is applied for the syntax elements described below.