Colour–colour diagram (g − r vs. g − i) of dwarfs with the density of the scatter plot shown using colour map. The fit to the relation (black solid line) is included. The definition of galaxy colour adopted by T21 and T24 (black dotted line; g − i = 0.6) and the corresponding value used in this paper (red dotted line; g − r = 0.452) is included. The histograms show the fraction of galaxies in each axis.