Stokes-I spectra of straylight corrected profiles I^* for different straylight scaling factors α of the fully split 15648 Å line. Shown here is an average over selected umbral pixels where the magnetic field is assumed to be parallel to the LOS, to demonstrate the principle of the correction method. Lower graph: uncorrected profile where a central lobe is still present. Graph in the middle: corrected case where the intensity level at the line center meets the continuum level. Uppermost graph: example of overcorrection.