Spectrally averaged signal in I, Q/I, U/I, V/I of FISS-SP (left) and HINODE/SP (right). In both cases V was multiplied with the sign of the first and Q, U with the sign of the second derivative of I before averaging. Unlike integrating the absolute value of the Stokes spectra, this procedure results in a predominantly unsigned polarimetric signal, but avoids the creation of single signed noise. This ensures that when integrating spectrally the signal accumulates, but the noise averages out. See text for further discussion.