This Photo Is Black And White. Here’s The Science Behind Why Your Brain Perceives It As Color

Image credit: Manuel Schmalsteig CC-BY-2.0/Øyvind Kolås

There’s a new viral optical illusion doing the rounds on the internet just now, and it’s fascinating!

If you take a look at this image, especially from afar, you will perceive it as a color image. But if you look very closely, you will see that the image itself is actually black and white,  with a colored grid layered over it.

Software developer and digital media artist Øyvind Kolås created this as a visual experiment, which he calls the ‘colour assimilation grid illusion’. The effect is achieved by laying a grid of highly saturated colored lines over the black and white image.

Kolås explains on his Patreon page:

“An over-saturated coloured grid overlaid on a grayscale image causes the grayscale cells to be perceived as having colour” 

Image credit: Manuel Schmalsteig CC-BY-2.0/Øyvind Kolås

So you might be wondering what is actually going on to make our brain perceive the image as color.

Vision scientist Bart Anderson from the University of Sydney, explains that the fact we see it this way is not so surprising. He told ScienceAlert

“The colour system is what vision scientists refer to as ‘low pass’, i.e., many of the receptive fields that code colour are quite large. So the grids get ‘averaged’ with the achromatic background, which then gets attributed to that part of the image.”

In simpler terms, when we look at things our brain kind of compresses the information received to give us an overall impression of what’s there without us having to examine closely.

Just a little bit of colour is enough to tell our brain what the colour of the whole object should be.

The photo we have shared is not actually the main one that went viral. Some of the people in the original photo did not give their permission for it to be shared, but this photo still demonstrates the effect just as well.

Kolås found that colored grids offer the best effect, but the effect can also be achieved using dots or lines:

Image credit: Manuel Schmalsteig CC-BY-2.0/Øyvind Kolås

“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”

And here’s an example using lines:

Image credit: Manuel Schmalsteig CC-BY-2.0/Øyvind Kolås

And here’s the effect on another black and white photo:

And if you think that is amazing, you’ll be even more impressed to see that the effect can also be applied to full-motion video as well as static images.

Kolås wins the internet today!