Evil or good? painting?

someday a friend of mine told me that he once saw a weird affecting pic of Jesus Christ, the picture after which you look at, you simply get bewitched by, that even afterwards within whiles you keep seeing that pic you saw for long in your eye sight. An optical illusion-like or stuff, he also told me that he kept seeing it for long whiles in every place he went through. Do you know what was that? or the name of this magic picture? or what can it be categorized to?