An outlandish picture created by digital artist and software developer Oyvind Kolas is spreading on the Internet. He decided to show how we can "trick" our perception and make us see bright colors where in reality there are only different shades of gray. Kolas called his method "the illusion of color assimilation."
In short, he superimposed on a black-and-white picture a network of bright dots, moreover, of the same shade. Because of this, the brain begins to think that the light gray and dark gray parts of the image have their own colors and "thinks out" the most logical ones. The method works great if you use thin raster lines instead of points. And with its help it is easy to "color" a black and white video - see an example.
Scientists do not see this as unusual, because this is how our perception of colors works. We see a huge number of shades and various small details, the vision system is capable of this. But the brain is unable to process such a volume of information, so it automatically "compresses" the picture, simplifies it. And in order to see the details, you need to purposefully concentrate on the object. Therefore, in a situation where we just see something, a small intervention, like a bright dot on a gray background, is enough to trick the brain into seeing something that does not exist.