Mystery Hunt 1996 / Puzzle 1B

The Instructions

Achilles
Hey, I recognize this picture! It's Escher's lithograph Above and Below.
Tortoise
Very astute, Achilles. I don't think I've ever seen it before. It looks pointillistic. Were all those colored speckles in the original work?
Achilles
No, not at all. It looks to me as though someone took a black-and-white scan and randomly sprinkled colored dots all over it.
Tortoise
I know you won't believe this, but this reminds me of the MU-picture in Hofstadter's book.
Achilles
I know you won't believe this, but I was thinking the same thing. How curious...