The same idea as palette, but the twenty-one ramps here are drawn from art movements and cultural traditions rather than generated from waves. Bauhaus, ukiyo-e, and so on. Each is a set of five colours.
Brightness picks a position along the set, and smoothness decides whether the colours blend into one another or meet at hard edges. At zero you get five flat bands, which is closer to how the original palettes were actually used.
repeat runs through the set several times across the tonal range, and rotation cycles the whole mapping over time.
One small guard is worth mentioning because it is a classic bug: pure white maps to exactly the end of the range, which wraps around to the beginning, so the brightest pixels in a picture would come out the darkest colour. The effect scales the input a hair short of the top to prevent it.