Back in the 80's I worked with a lady that had the north American rights for t-shirts in all things Escher. I did a good deal of the graphic arts photography (how you did prepess pre computer) for the t-shirts. got to handle the original prints of most of the common Eschers you see. They have amazing detail that you usually don't see in reproductions. I used to say a good looking halftone is a terrible halftone as part of it is compensating for ink spread. A deep black on a normal press is about 85% black, even more grey if it was going to newsprint. For the shirts we were down to 40-50% as there was considerable ink spread in the silkscreen process...