Professor Jacques Ninio is fascinated by the type of illusion first presented as the so-called Ouchi Illusion. I must confess that I have never found the Ouchi Illusion to be impressive, and alas I didn't find some of Prof. Ninio's variants impressive either. However, the one above is very striking! Scroll back up and stare at it for a while. You will gain the very strong impression that the parabolic section at the bottom is in front of the background, and further is made of thick plastic, which shows reflections at the curved leading edge! All this, in a simple black-and-white design. As for the Ouchi Illusion, here is the best on-line version I have found; one of very few on-line versions that works.

I find that the original illusion discovered by Hajime Ouchi can be improved by tilting it (as at left) or by using a dark color other than black (as at right). Indigo might be best. If you are unfamiliar with the illusion, and didn't click the explanatory link above, looking fixedly at either the right or left image will give the impression that the central disk is detached from the "frame," floating either in front of or behind it. Moving your head actually gives the impression of a perspective, with the central disk showing illusory parallax relative to the frame. For a very good presentation, check out the Flash-animated version in the middle of this page.

Jump to Illusion 25, 50, 75, 100, 110, 120,  130, 140.

An extremely nice collection of very colorful illusions, many of which were new to me.

Individual Project LITE pages are linked elsewhere on these illusion pages, but here's the full directory.

Individual ZONEFLASH animated illusion pages are linked elsewhere on these illusion pages, but here's the full directory.

Although Akioshi Kitaoka's illusion pages are randomly distributed, like the ones you are looking at now, there actually is an index, here.

A long article on illusions, with dozens of animated illustrations.