A computer implemented method. The method includes obtaining, using a processor, spectral reflectance data from a coated surface having a target coating theron; and determining, using the processor, whether the data includes any outlier data points. The method also includes removing, using the processor, at least one of the outlier data points to produce final spectral reflectance data; and calculating, using the processor, a characteristic of the target coating based at least in part on the final spectral reflectance data.