Voilà une surprenante illusion d’optique créée par Edward H. Adelson, professeur de science de la vision au MIT en 1995.
Sur cette scène en 3D, les carrés marqués A et B sont de la même couleur. Difficile à croire, et pourtant voici l’explication en anglais suivie de la preuve en image.
J’ai vérifié à l’aide d’un logiciel de retouche photo, en prenant un échantillon de chaque case, et c’est effectivement la même couleur !
The visual system needs to determine the color of objects in the world. In this case the problem is to determine the gray shade of the checks on the floor. Just measuring the light coming from a surface (the luminance) is not enough: a cast shadow will dim a surface, so that a white surface in shadow may be reflecting less light than a black surface in full light. The visual system uses several tricks to determine where the shadows are and how to compensate for them, in order to determine the shade of gray “paint” that belongs to the surface.
than its neighboring checks is probably lighter than average, and vice versa. In the figure, the light check in shadow is surrounded by darker checks. Thus, even though the check is physically dark, it is light when compared to its neighbors. The dark checks outside the shadow, conversely, are surrounded by lighter checks, so they look dark by comparison.
ual changes in light level, so that it can determine the color of the surfaces without being misled by shadows. In this figure, the shadow looks like a shadow, both because it is fuzzy and because the shadow casting object is visible.
amp; or lighting.
in view.
Jeu de briques
Snake
Pacman
Bubble