Crater illusion
An apparent convex changes to an apparent concave, vice versa, when the image is rotated through 180 degrees.
since January 18, 2013
A standard image, which shows an apparent concave in the center of the left image and an apparent convex in the center of the right image.
Figure-ground reversible images
Looks like a caldera.
Blue craters
"A red blood cell and a red hat"
The center of the left disk appears to be concave while the center of the right one appears to be convex.
Copyright Akiyoshi Kitaoka 2013 (January 18)
Colored standard images
Figure-ground reversible images
"Double moats and double embankments"
Figure-ground reversible images
Square crater illusion
"Canal and bridges"
Multi-square crater illusion
Figure-ground reversible images
Rings of the crater illusion
Ramachandran's crater illusion
Bevel, a crater illusion
Crater illusion and the optimized Fraser-Wilcox illusion Type IIa
"Legs of an octopus"
Crater illusion
Copyright Akiyoshi Kitaoka 2013 (January 18)
"Rotation of crater rings"
The left ring appears to rotate counterclockwise while the right clockwise.
Copyright Akiyoshi Kitaoka 2013 (January 18)
cf.
"Coil springs"
Bright regions appear to be in front and dark ones behind. This is not the crater illusion.
Copyright Akiyoshi Kitaoka 2013 (January 18)
Copyright Akiyoshi Kitaoka 2013 (January 18)