A method and system for a color xerographic machine determines a lower bound for the ROS power levels so that color defects are not produced by light attenuation from one or more layers of toner particles on a latent image. The method computes a minimum ROS power level for the photoreceptor at its maximum and minimum charge levels. The minimum ROS power level is the level at which the discharge voltage does not drop beyond a maximum discharge voltage difference. The difference is related to a toner particle density that affects color reproduction. The minimum ROS power levels for the minimum and maximum photoreceptor charge levels are used to compute a functional relationship for minimum ROS power levels at other photoreceptor charge levels. Thereafter, the minimum ROS power level function may be used to compute minimum ROS power levels for other photoreceptor charge levels. The computed minimum ROS power levels may be used to control the power levels used during color reproduction performed by the machine.