An analytical method for estimating the correlated colour temperature uncertainty

Correlated colour temperature (CCT) is an important parameter of light sources. It is estimated from the position of the chromatic coordinates (u, v) in the Commission Internationale de l'Éclairage (CIE) 1960 colour space. The International Organization for Standardization (ISO) Guide is difficult to use when trying to obtain CCT uncertainty from chromaticity coordinates and their uncertainties because there is no clear analytical expression relating them. In this paper, an analytical method of obtaining the CCT uncertainty from the coordinates (u, v) and their uncertainties, without approximations, is proposed. The validity of the method is proven by comparing results with examples in the literature and with those obtained using a geometrical projection method.