This optical illusion appears to be 3D but it's actually something completely different

On social networks, a two-dimensional image gives the impression that it is in 3D. The effect is quite stunning.

Optical illusion
Optical illusion

Every week brings new optical illusions. Just when you think they will never surprise you again, new images appear in our feeds and manage to trick our guard. After several stories of illusion, we introduce you to this new riddle called chrome stereoscopy.

Discover our latest podcast

3D fever

Avatar 2: The Way of the Water is about to be released in cinemas and reminds us that its prequel, Avatar, revolutionised the film industry. Remember, after its release, the cinema was flooded with a 'new' technology 3D! Present in cinemas, on our screens, on our phones and even on a certain Nintendo handheld console, 3D has obsessed us for many years, and it is the idea of having depth on a flat surface is intriguing.

This tweet translates to:

Do you know chromosteroscopy? In Greek, chromo means color and stereo volume. A two-dimensional image can give a sense of depth through color contrast. Bluffing no?

But as the 3DS proved, you don't necessarily need to wear special glasses to get the 3D effect. There's a little trick to achieving a similar result with little effort.


An image posted on Twitter that has quickly gone viral uses the principle of chrome stereoscopy to create a 3D effect. Rather simple, this illustration only features a kind of 'archery target': a red dot surrounded by a blue circle, itself surrounded by a larger red circle, all on a black background. If we focus on the central red circle, something rather strange happens: the blue circle seems to be moving away from us!

Astrophysicist Eric Lagadec, who posted the photo on Twitter, explains the principle:

In Greek, chromo means colour and stereo volume. A two-dimensional image can give an impression of depth through colour contrast.

This article was translated from Gentside FR.

Blue: This colour may actually be an optical illusion Blue: This colour may actually be an optical illusion