The present disclosure relates generally signal processing. One claim recites an apparatus comprising: memory for storing a color video signal comprising first data and second data; and a processor. The processor is programmed for: modifying first color information and second color information of the first data by encoding a signal in the first color information such that the signal includes a first signal polarity, and encoding the signal in the second color information such that signal includes a second signal polarity that is inversely related to the first signal polarity, and modifying first color information and second color information of the second data by encoding the signal in the first color information such that signal includes the second signal polarity, and encoding the signal in the second color information such that the signal includes the first signal polarity. Of course, different combinations and claims are provided too.