A feedback control method for controlling an ununiform banding on a photoreceptor is disclosed that includes arranging optical sensors on a photoreceptor, transferring an amount of toner on a piece of paper, measuring the resulting amount of banding, and adjusting the parameters to decrease the amount of banding. A method of measuring low deposited masses of a substrate is disclosed, using either ETAC optical sensors or full width array sensors. Finally, a copy is disclosed including at least one of NC2 array sensors and ETAC sensors, a developer roll voltage source, a ROS intensity source, an input device and a controller.