ISO/DIS 3664:1998 imposes new requirements on D50 illumination in an attempt to tighten the tolerances on D50 sources. This paper intends to discuss a few potential problems and some implications in implementing the newer standard regarding D50 sources.
Chengwu Cui, "New Requirements on D50 Illumination in ISO/DIS 3664:1998 and the Implications" in Proc. IS&T 7th Color and Imaging Conf., 1999, pp 205 - 211, https://doi.org/10.2352/CIC.1999.7.1.art00038