1. A scaling system for scaling a bitonal image, comprising: a polarity detection system for detecting a polarity of the bitonal image; a pixel reduction system that generates a scaled image by reducing pixel pairs down to single scaled pixels by selectively applying either a normal or reverse set of pixel reduction rules, wherein an applied set of pixel reduction rules is determined based on a detected polarity; and a line density control system that allows the scaled image to be made lighter or darker by changing the applied set of pixel reduction rules.