The figure in the circles is actually square.
Are these actually squares?
Sander Paralelogram ~ 1926
Measure the diagonals - you'll be surprised
Life ~ The Fraser Illusion
Are the letters really crooked?
Are you looking at the inside or the outside of this card?
Look at this picture for a couple of seconds and bring your face closer to the screen.
The woman will seem to join herself back together.
Alternatively you can bring the monitor closer to your face, if you like)
The above picture reminded me of a childish amusement.
Hold your hands with the tips of your index fingers touching.
Bring your hands towards your eyes.
Hey presto ! Sausage fingers.
Are these rows really parallel?
Thanks to Peter Shearn for reminding me of this building at the bottom of St Michaels Hill, Bristol
Please scroll down for some more pictures of the tiles
This really is an optical illusion, the tiles are perfectly rectangular!
Even when damaged and dirty the illusion shows through !
How can a two dimensional image show bumps and hollows?