These come from a post in the always wonderful BibliOdyssey. They purportedly represent colour schema as conceived by various thinkers, from Pythagoras to a certain Michel Albert-Vanel; and are all taken from The Colour Museum - which I attempted to browse, but soon became overwhelmed by the topic and navigation.

If you want to know more about the origin of these great prints visit the original post at BibliOdyssey or indeed The Colour Museum.