Thank you for your comment and question @midlet! hmm I am not so technical and I like to experiment so I never really know how it'll end but in this case (page), we're in a rather metallic, nano-based environment, thus the greenish/bueish tones (with rusted parts, because everything is billions of years old). The average colours are also a bit dictated by the "zone" from the "Hyperhedron" (that universe where the story takes place) where we are. So I'd say it is always a mix of the colours I want to see and unexpected results than a very planned idea.