Result of denoising the positive and negative sections (shown together) of the spectrum shown in Fig. 5a with positivity and negativity constraints respectively. Note the reduced ringing, which leads to a more representative result with respect to the number of true features. Once again the FDR denoising of our noisier example (Fig. 5b) yields a null spectrum (not shown), and would thus result in the discarding of this spectrum from the redshift analysis.