This three-dimensional effect rests in the eye of the beholder, and frustratingly, not every beholder can see it. Magic Eye products of the mid-'90s (by N.E. Thing Enterprises, later renamed Magic Eye, Inc.) consisted of stereoscopic images concealed in a bewildering pattern of dots of colors. The trick is to get your eyes to defocus in such a way that the patterns coalesce into a three-dimension image.
Some people can get a Magic Eye to resolve without a problem. Others can never get it to work. This hit-and-miss success rate was the focus of much pop culture chatter in the mid-1990s, culminating in a famous episode of Seinfeld wherein a character misses a week's worth of important business meetings when he becomes so obsessed with getting the Magic Eye to work.
