In an image-on-image (IOI) color processing system, which superimposes toner images of different color separation toners onto a photoreceptor, a method for determining composite toner coverage on a page includes determining the order in which the color separations will be printed; determining an attenuation factor for each individual color separation and for all combinations of the color separations; determining a fractional amount of toner that is requested for each separation; and summing the fractional amounts of toner requested for each separation times the fraction of the substrate that is not yet covered by prior separations, and the amounts of toner that are deposited on each of the prior separations times the attenuation factor corresponding to that combination of prior separations, in all combinations. These revised coverages can be used to adjust the input values of an image before it is used in a reload detection method.