A marking device is controlled to mark a media sheet with halftone dots selected from a set of image halftone dot representations. The marking device is controlled to mark a monitored surface with halftone dots selected from a set of control halftone dot representations to form test patches of different nominal marking densities. Measured marking densities are acquired using a density sensor for the test patches marked on the monitored surface. The set of control halftone dot representations is updated based on the measured marking densities and the nominal marking densities.