Black and white or coloured? Another viral optical illusion leaves internet baffled

A bizarre and brilliantly effective optical illusion going viral on the internet tricks your brain into seeing a colour image, but if you look closer, you’ll notice the photo you’re staring at is only black and white.

Oyvind Kolas has produced a number of images in which he uses a “colour assimilation grid illusion” over black and white photographs to trick the brain into seeing a full-colour picture.

“An over-saturated coloured grid overlaid on a grayscale image causes the grayscale cells to be perceived as having colour,” Kolas explains on his Patreon page.

His work is not just limited to photographs and still images. He has created a video where the colour grid is laid over moving characters.

The illusion isn’t just created by using coloured grids, either. While Kolas finds grids offer the best effect, he’s also played around with other ways of achieving the visual trick, using alternatives like dots and lines:

“The raster of dots gives a nice analogy to half-toning as used in print, where colour assimilation aids the optical mixture of colours that already happens before our visual system gets involved,” Kolas explains on his Patreon page.

We see colour because the brain pieces together all of the information that the rods and cones collect, and it often fills in “missing” parts in order to interpret the world around us.

Around 8% of men and 1% of women have difficulties seeing some colours, commonly known as colour blindness, and therefore they may perceive these pictures differently.