A new two-stage illumination estimation method based on the concept of rank is presented. The method first estimates the illuminant locally in subwindows using a ranking of digital counts in each color channel and then combines local subwindow estimates again based on a ranking of the local estimates. The proposed method unifies the MaxRGB and Grayworld methods. Despite its simplicity, the performance of the method is found to be competitive with other state-of-the art methods for estimating the chromaticity of the overall scene illumination.
Lilong Shi, Brian Funt, "Rank-Based Illumination Estimation" in Proc. IS&T 21st Color and Imaging Conf., 2013, pp 118 - 121, https://doi.org/10.2352/CIC.2013.21.1.art00021