Method to Obtain LED Spectrum Optimizing Protection Effect and Color Quality for Lighting Dyed Cultural Relics Painted with Inorganic Pigments

Spectral radiation could cause color damage to dyed cultural relics, and finding a method to obtain a minimum-damage light source is a key issue to be solved. In this paper, the color change behavior of pigments under exposure was experimentally investigated by irradiating 17 typical inorganic pigments used for dyed cultural relics with 10 different narrow-band LED light sources. Through an analysis of the color difference of the test pigments against the amount of exposure, the responsivity equations of the pigments were obtained and a mathematical model for predicting the color damage degree was proposed. The 10 kinds of narrow-band light were combined to obtain 106 LED by using the exhaustive method. The Ra, R9, and | Duv | value of the above spectra were calculated. Ra≥90, R9≥0, and | Duv | ≤0.0054 were taken as the evaluation basis, and 35,398 spectra that met color rendering requirements were obtained. The established mathematical model was used to calculate the color damage value to find the minimum-damage spectrum, which was then input into a Thouslite LEDCube system for reduction. An experiment was conducted among the minimum-damage LED and 3 randomly selected light sources, and results showed that the minimum-damage LED light source has an obvious illumination protection effect.