Gradient Map is such a powerfull tool on other drawing softwares like PHotoshop and I would love to use it in Harmony.
It’s basically a way to map a gradient to the light and dark values of an art. Many artists shade their art in only grayscale and then use gradient maps to color it in an interesting way
This small part of this video shows it in action. I don’t think it should be too hard to implement it.