Correction factors for the ALR and PTR parameters of magnetic-head sliders are determined by calculating an effective reflectivity and a corresponding PCOR at each pixel of the air-bearing surface. The absolute value of reflectivity at each pixel of the AlTiC air-bearing surface is obtained from an empirical equation relating it to modulation. The ratio of Al2O3 and TiC in the AlTiC surface is then calculated at every pixel assuming a linear relationship between the absolute value of AlTiC reflectivity and the theoretical reflectivity of each constituent. The linear relationship is then also used to calculate the effective (complex) reflectivity for the AlTiC material from the relative concentrations of Al2O3 and TiC at each pixel.