The Checkerboard illusion

Move the cursor over the image below to place a mask over the checkerboard pattern, leaving visible only squares A and B...

(Note that the mask might take a little while to load: the images are fairly large.)

An explanation of the effect can be found on the control page. Square B is, however, slightly darker than A: the mask isn't affecting the shades, merely removing the other visual cues.

This illusion was designed by Edward H. Adelson. Visit his website to see more examples.
Click here to return to the control page.