Afterimages (sometimes calles ghost images) are optical illusions that appear in one's vision after the exposure to the original picture has ceased (eg. the bright glow after looking into strong light). This persistence of vision allows a rapid series of pictures to portray motion, which is the basis of animation and cinema.
A few famous afterimages include illusions of Jesus, Che Guevara, US flag or Italian flag.
Stare at the four black dots in the center of the image for 30 - 60 seconds. Then quickly close your eyes and look at something bright (like a lamp or a window with sunlight coming through it). You should see a white circle with an image inside it.
Stare at the image for at least 30 seconds and then look at something white to see Che Guevara afterimage.
Stare at the red dot on the girl's nose for 30 seconds. Then look at the ceiling (or any white surface) and blink really quickly a few times. You will be amazed to see colorful girl.
Stare at the image for at least 30 seconds and then look at something white to see Italian flag afterimage.
Stare at the image for at least 30 seconds and then look at something white to see US flag afterimage.
Stare at the red dot in the middle for a few seconds. After the time runs out, you'll see colored town while there is actually only black and white.
Stare at the black dot in the middle for 15 seconds and then you'll see a colored castle. Actually it's only black and white. Click the following link for animation.
color castle illusion
