Systems, methods, and apparatuses are provided for identifying an optimal spectral match and potentially display the compared spectra. A sample spectrum of a sample substance can be compared to reference spectra to identify matches, thereby determining possibilities for what the sample substance is. Correction parameter(s) may be used for the sample spectrum and/or the reference spectrum. Initial value(s) for the correction parameter(s) can be applied to the sample spectrum and/or a reference spectrum, and a similarity score can be determined. The value(s) for the correction parameter(s) can be updated and iteratively improved to provide an optimal similarity score that satisfies a convergence criterion. Data about the reference substances having optimal similarity scores that are above a threshold can be output to a user, e.g., the reference spectra can overlay the sample spectrum. A user can then make a final determination of which reference substance corresponds to the sample substance.