Individuals with normal colour vision and those with Protanomaly (red colour weakness), deuteranomaly (green colour weakness), and tritanomaly (blue colour weakness) are called Trichomates --i.e. they have all three cones, system but one is weak.> Dichromates: only two cone system present, E.g. Protanopia = red cone absent; Deuteranopia = green cone absent Tritanopia = Blue cone absent.">