Loci of colour stimuli in the colour diagram reconstructed with the CIELAB model of colour vision.
Green points represent the colours of leaves, blue and red points represent blue and red facial colours, respectively, in the a*b* plane of CIELAB. Leaves with outlying a*b* values are not represented (min a* = −18.4; max b* = 56.1). In CIELAB, one unit corresponds to one just noticeable colour difference. Grey shadings indicate 95% confidence interval of hues. Coloured shadings indicate predicted hues of maximal disparity against the other facial colour and the background. For example, the blue shading indicates the predicted blue hues of maximal contrast against both leaves and red colours. The construction of the blue shading is illustrated with blue lines and marks of equal angles. Top-ranked males are the most saturated for both blue and red colours as indicated by the arrows.