Image forming apparatus with predictive electrostatic process control system

An electrostatographic printing machine having a charge control system incorporated therein, wherein first and second surface voltage potentials on the imaging surface are measured to determine a dark decay rate model representative of surface voltage potential decay on the imaging surface with respect to time, and the dark decay rate model is used to determine the surface potential voltage at any point on the imaging surface corresponding to a given charge voltage. This information is used for providing a predictive model to determine the charge voltage required to produce a target surface voltage potential at a selected point on the imaging surface.