Fig. 5. Spectral loci (M_R, M_G and M_B) of points 1-12 in Fig. 2 plotted within the equilateral red-green-blue colour triangle, the colourless centre of which is represented by +. The rectangular areas of the colour triangle are enlarged and shown next to the triangle, with arrows starting from the spectral locus of real colours perceived by a polarization-blind retina with P_B=P_G=P_R=1 and ß_R, ß_G, ß_B = arbitrary, while the arrowheads point to the spectral locus of false colours perceived by a polarization-sensitive retina with P_B=P_G=P_R=2, =0°, ß_R=145°, ß_G=35° and ß_B=0°.