Greyscale half-inversion.

https://github.com/janvancoppenolle/LUT/tree/main/Solarizers
  Input Curve

Solarize

Luminance-desaturated 50% negative.
  Result Curve

Sabattier

Lightness-desaturated Exclusion-blend 50% negative.
  Result Curve

Saturation

While the above two methods work equally well on greyscale and colour images, this one reveals the saturation of colored pixels (turning grey pixels black).
  Result Curve (N/A)