Conventional light sources (e.g., fluorescent) contain UV/violet radiations that can excite the fluorescent whitening agents (FWAs) in man-made and natural white objects to enhance whiteness appearance and create different degrees of white. Typical white-light LED sources, however, contain little UV/violet radiation to increase its luminous efficacy. In this study, we investigated how the failure of white-light LEDs to excite FWAs affect the image color appearance with different white balance algorithms. A same setup, including a Macbeth ColorChecker and three whiteness standards with different amount of FWAs, were illuminated by two 6500 K illuminants with different levels of UV/violet radiation. The captured RAW images were white balanced using 10 algorithms. It was found the failure of FWA excitation produced noticeable color differences, with an average ΔE from 2.9 to 8.1 in the CIELAB color space. The algorithms based on the Gray World assumption were generally less sensitive to the FWA excitation, in comparison to those based on the Retinex theory.
Siyuan Chen, Minchen Wei, "White Balance under White-light LED Illumination" in Proc. IS&T 26th Color and Imaging Conf., 2018, pp 140 - 144, https://doi.org/10.2352/ISSN.2169-2629.2018.26.140