Optical illusions

[Sean]

The check shadow illusion is the most convincing optical illusion I've ever seen: I can well imagine people giving evidence in court that the two squares (when you click on Question 1) are different shades of grey. But they're exactly the same shade. I find the only way to really know it is to get a few pieces of paper or such to block off the surrounding squares so you can just look at the pixel areas in isolation.

http://www.michaelbach.de/ot/lum_adelsonCheckShadow/index.html


Another favorite-

http://www.procreo.jp/labo/silhouette.swf

Scroll down page for double image with extra lines to compare-
http://en.wikipedia.org/wiki/Talk:The_Spinning_Dancer

(I wrote the most of the explanation on the main article.)


Some more from the same site

http://www.michaelbach.de/ot/lum_adelson-plaid/index.html

http://www.michaelbach.de/ot/ang_hering/index.html

http://www.michaelbach.de/ot/ang_poggendorff/index.html

http://www.michaelbach.de/ot/ang_cafewall/index.html

http://www.michaelbach.de/ot/ang_trianglePuzzle/index.html

http://www.michaelbach.de/ot/sze_muelue/index.html

http://www.michaelbach.de/ot/sze_t-illusion/index.html

http://www.michaelbach.de/ot/sze_shepardTables/index.html

http://www.michaelbach.de/ot/sze_shepardTerrors/index.html

http://www.michaelbach.de/ot/cog_hiddenBird/index.html

http://www.michaelbach.de/ot/mot_feet_lin/index.html

http://www.michaelbach.de/ot/mot_freezeRot/index.html

http://www.michaelbach.de/ot/mot_motionBinding/index.html

http://www.michaelbach.de/ot/mot_pinna-brelstaff/index.html

http://www.michaelbach.de/ot/mot_spokes/index.html

http://www.moillusions.com/2006/05/elephant-optical-illusion.html

http://en.wikipedia.org/wiki/Image:LargeTribarGotschuchenAustria.JPG

The grey bar is one colour
http://en.wikipedia.org/wiki/Image:Gradient-optical-illusion.svg

Chequer shadow illusion- squares are the same colour (strong illusion)
http://en.wikipedia.org/wiki/Same_color_illusion

The grey bars are all the same colour
http://en.wikipedia.org/wiki/White%27s_illusion

Barber's pole
http://en.wikipedia.org/wiki/Image:Barber-pole-01.gif

The impossible trident
http://en.wikipedia.org/wiki/Image:Blivet.svg

The photos of the tower are identical
http://en.wikipedia.org/wiki/Leaning_tower_illusion

Cafe wall (the lines are straight)
http://en.wikipedia.org/wiki/Image:Caf%C3%A9_wall.svg

& a building in this design
http://en.wikipedia.org/wiki/Image:Port1010DigitalHarbour.jpg

Impossible staircase
http://en.wikipedia.org/wiki/Image:Ascending_and_Descending.jpg

The two blue lines are the same length
http://en.wikipedia.org/wiki/Image:Sander_Illusion.svg

The two circles are the same size
http://en.wikipedia.org/wiki/Image:Mond-vergleich.svg

They are circles, not spirals
http://en.wikipedia.org/wiki/Image:Fraser_spiral.svg

Black dots appearing and disappearing
http://en.wikipedia.org/wiki/Image:Grid_illusion.svg

The lines are straight
http://en.wikipedia.org/wiki/Image:Hering_illusion.svg

The shapes are identical
http://en.wikipedia.org/wiki/Jastrow_illusion

The spots only disappear but look like are replaced with a lilac spot
http://en.wikipedia.org/wiki/Lilac_chaser

The lines are the same length
http://en.wikipedia.org/wiki/Image:Mueller_lyer.svg

The square looks distorted
http://en.wikipedia.org/wiki/Image:Orbison_illusion.svg

Impossible triangle
http://en.wikipedia.org/wiki/Image:Penrose_triangle.svg

The lines are parallel
http://en.wikipedia.org/wiki/Image:Zollner_illusion.svg

Cornsweet (the two halves are the same colour)- not works well on projected screen http://en.wikipedia.org/wiki/Image:Cornsweet_illusion_explanation.svg

The image seems to move- but do esn't move on projected screen
http://en.wikipedia.org/wiki/Image:Anomalous_motion_illusion1.png

Impossible cube http://upload.wikimedia.org/wikipedia/commons/e/ec/Necker_cube_and_impossible_cube.PNG

Missing square, but really the triangle is smaller- doesn't work on projected screen well
http://en.wikipedia.org/wiki/Missing_square_puzzle

Also some good ones to scroll through on this video, up to 6mins- but don't work on the projected screen
http://kr.youtube.com/watch?v=OQxNjyupeTo