We present an algorithm for the selection of high contrast color sets which performs very well and does not require that the function adopted to code the similarity between two colors is a distance function.
P. Campadelli, R. Schettini, "Selection of High Contrast Color Sets" in Proc. IS&T 4th Color and Imaging Conf., 1996, pp 91 - 93, https://doi.org/10.2352/CIC.1996.4.1.art00025