According to the invention, a method is provided for calculating a Fractional Area Coverage (FAC) for determining the density of toner to evaluate the effectiveness of a xerographic printing process. The amount of diffuse light being reflected at the specular angle is determined during densitometer calibration and subsequent specular sensor readings are corrected by subtracting a fraction of the diffuse sensor signal from the specular sensor signal. Also provided is a computer readable media having stored computer executable instructions, wherein the computer executable instructions, when executed by a computer, directs a computer to perform a method for calculating a FAC for determining the density of toner to evaluate the effectiveness of a xerographic printing process.