S-curve Generator

I can’t count how many times I’ve wanted a curve-generator like this and have hacked partial solutions. It is often used as a lookup table to shift levels for an image contrast adjustment, or shift motion or timing to advance or slow motion while keeping the total time the same.

Starting with a linear ramp (representing no change) and a half-sine wave (representing an ease-in-ease-out) and three sliders, it gives a nice family of curves with properties I often need:

left-to-right always rising from 0 to 1. control the tangent at the start and end, how fast it rises from low to high in the middle, and a left-right bias.

Anyway, try it on any image with the Lookup TOP for example. (For color images you may want to convert RGB to HSV, apply lookup to V (blue channel) and convert back to RGB.)

And have a look inside to see how it’s assembled.

NOTE: This component is now in the Palette of 088 build 50000 and later.


SCurve.tox (4.25 KB)

wow! just grabbed this… gonna make compositing a lot more fun :mrgreen:

I replaced the SCurve.tox with a slightly-improved version where you can optionally connect a CHOP or TOP to an input and have the curve automatically applied to it.

The Crossover slider lets you get tighter zero-crossing curves too.

NOTE: This component is now in the Palette of 088 build 50000 and later.