A spectral processor (118) includes a first processing channel (120) that generates a first spectral signal derived from a detector signal, wherein the first spectral signal includes first spectral information about the detector signal, and a second processing channel (120) that generates a second spectral signal derived from the detector signal, wherein the second spectral signal includes second spectral information about the detector signal, wherein the first and second spectral signals are used to spectrally resolve the detector signal, and wherein the detector signal is indicative of detected polychromatic radiation.