1. A method of halftoning a color image, comprising: for a color component of a current pixel, comparing an error value to a threshold to determine whether to output a pixel for a current color plane, the error value including diffused error from previously-processed pixels of the current color plane, the error value adjusted based upon a first error contribution from a previously-processed color plane of the current pixel, the error value further adjusted based upon a second error contribution from a previously-processed pixel of a color plane that has not yet been processed for the current pixel.