Optical illusions play tricks on the brain, making us question the reality of what we are seeing.
Such images force us to look again and scratch our heads in an attempt to make sense of them.
One picture of an oddly dressed man has gone viral on the internet thanks to the strange scene it depicts.
The image, posted to Imgur in January 2014 by an unknown user, continues to resurface regularly on the forum.
It depicts a tall man with a bushy ginger beard and sideburns covering most of his face.
The man is already an unmissable sight thanks to his highly distinctive and eccentric dress sense.
He is wearing an all purple outfit consisting of baggy harem trousers, a purple T-shirt and a purple top hat.
The man is also barefoot and wearing several cloth ankle bracelets, in addition to a long cream scarf around his neck.
But the man’s dress sense is not the most peculiar thing about the image.
He appears to be a giant in the photograph, thanks to a clever optical illusion.
Two men are standing behind him on the edge of a swimming pool.
The two tiny figures appear to be so small barely reach the ginger bearded man’s knee.
The image is captioned: “Already tall (7ft or more) friend accidentally takes optical illusion photo.”
It has received 8,229 points and 116,461 views on the Imgur platform since it was first uploaded.
However, clever Imgur users have worked out exactly what is wrong with the image.
It is a trick of perspective because the man is standing on a ledge which is much higher than the people behind him.
One user wrote: “He’s standing on a higher level, that’s why his shadow cuts off.”
Another agreed, writing: “Ohhhh, I see it, he’s actually at the edge of a ledge, you can see his shadow cutting off… Well played OP.”
Another optical illusion image to go viral involved a pink and yellow pattern. Viewers are asked whether the lines are parallel or not.
When looking at the image it first appears that the lines are not parallel at all, instead positioned at different angles on the shape.
However, it is the smaller cross-hatched lines that trick the eye. Once these lines are removed the pink lines are indeed parallel, much to viewers surprise.