The artists of German Expressionism preferred subjective emotions to the strict academic tradition, depicting modern cities, ...

and paintings representing key phases of the evolution of Jackson Pollock's abstract expressionism. "Multifractal analyses, even in one-dimensional cases, are computationally quite complex ...

So, expressionism is painting to show how you feel about something, rather than what it looks like, and you can use whatever colours you like to express yourself and of course with expressionism ...