1. A method comprising: halftoning a source image, the halftoning including error diffusion processing of a first separation of plural color separations of a pre-rendered image after error diffusion processing a second separation of the plural color separations of the pre-rendered image, the error diffusion processing of the first separation comprising, for respective pixel values corresponding to the first separation, choosing respective magnitudes of the respective pixel values as a function of the error diffusion processing of the second separation; and outputting a rendered image including the same plural color separations, the output rendered image being populated with, for the first separation, pixel information based on the respective magnitudes.