This image in particular made me wonder if there was some type of tracing aid involved. Maybe the dutch-looking street reminded me of Vermeer's method. I wonder what input device they were using? I was using a pretty nice input surface for doing CAD work sometime around 1990-93 on a PC, and we had occasion to lay transparencies on top and trace on them. I don't know if Macs 5 years before that had this type of peripheral. And anyway, there were certainly some special artists I knew of back then who could do this with a mouse and enough time.