For each channel, you can set Frequency (0-5) and Phaseshift
(0-360) of sine-cosine functions, using either sliders or input
boxes and their arrowheads.

Frequency around 0.3 to 0.7 provides a
curve that is similar to the linear function (original image),
only darker or with more contrast. As you raise the frequency
level, you'll get an increasing variation in pixel
transformation, meaning that the image will get more and more
“alien”.

Phase alters the value transformation. 0
and 360 degrees are the same as a sine function and 90 is the
same as a cosine function. 180 inverts sine and 270 inverts
cosine.