The present application is directed to an illumination device comprising a recycling cavity defined by recycling surfaces and a light emission surface; a light source within the cavity. A spectrum modifying layer is on a portion of the recycling surface, the spectrum modifying layer producing a spectral response different from the spectral response of the recycling surface. In some embodiments, the spectrum modifying layer shifts the spectral properties of the light being emitted from the light emission area from the spectral properties of the light source. In some embodiments, the spectrum modifying layer selectively absorbs a portion of light along the light source spectrum. In some embodiments, the spectrum modifying layer re-emits light at a wavelength longer than the wavelength it absorbed.