"Illusie van de Luciferdoosjes"The matchboxes optical illusion(See the interactive proof that they are the same, below)
In an essay in a book about M.C. Escher, Bruno Ernst wrote:
"It is also a misconception that Escher depicted optical illusions. Of course, Escher knew many optical illusions; he was interested in them and enjoyed them as well. Yet he never chose them as a starting point for a print. I will give one example here.
(Below) …you see two boxes. Our visual perception tells us that the left one is more elongated than the right. But if you take a piece of paper and cut it so it exactly covers the black side of the right box you will discover that the same piece of paper also exactly covers the black side of the left box. I asked a friend (Fred van Houten, who has made many impossible figures) to dress up the two boxes so they would appear more realistic… (the result is in the first photo above.)
Escher undoubtedly would have added this picture to his beloved collection of prints displayed on the door of his cupboard, but he would never have been tempted to make something like it himself. He was occupied with very different things. Dressing up optical illusions was entirely out of his scope."
Are the black sides equal?
These two matchbox illusions, one plain and one dressed up by Fred van Houten, were used as illustrations in the chapter called Selection is Distortion by Bruno Ernst (Hans de Rijk) in the book M.C. Escher’s Legacy: A Centennial Celebration by Doris Schattschneider, Maurits Cornelis Escher (M. C. Escher), and Michele Emmer.
The animated proof for "Illusie van de Luciferdoosjes"(The matchboxes optical illusion)
Fred van Houten’s website (in English)>>
Animated version of Illusie van de Luciferdoosjes>>
M.C. Escher’s Legacy: A Centennial Celebration, Google books>>