How do light pollution filters work? Do they actually help?

Light pollution reduction (LPR) filters work because many outdoor lighting sources do not shine evenly across the visible spectrum. Instead, they emit radiation at only a few distinct wavelengths. LPR filters suppress those and similar wavelengths while allowing others through. While a filtered view seldom shows more detail than an unfiltered one, or reveals an otherwise invisible target, LPR filters improve the visual aesthetics by darkening the background sky.