Scheme:   monochromatic contrast (base + complement) soft contrast (split complements) double-contrast (2 neighbors + complements) analogic (base + neighbors)

Distance [0 to 60]:   ?  0?- contrast, 60?- triade  Use it

Distance [-90 to 90]:   ?  (90?- tetrade)  Use it

Distance [0 to 60]:   ?  add the complement  Use it