LIGHT already spends its slope budget on the tone knees, so the two end
points were doing nothing a tone knob could not. On WB they act on each
channel's own distance from the end: the darker channel of a shadow and
the brighter channel of a highlight move most, which neutralises a cast
at the toe and the shoulder. Both shuffles stay cubic in the channel
value, so every channel's curve is still monotonic (>= 0.46).
3dtours
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