Do the colors on a computer screen only matter to us? What do other animals see on the screen?

We can see most of the colors in life on our computer screens, and we can even print out the colors displayed on the computer screen.

However, it may come as a surprise to many people that such colors only appear to us; other animals cannot see them at all.

So, the question is, why do computer screens only work for us? And what do animals see on computer screens?

How do computer screens display colors?

Most computers use RGB screens, which are made up of tiny dots called pixels, and each pixel is made up of three "basic" colors: red, green, and blue.

To do this, each pixel is actually designed to be composed of three small "dots" that emit different colors of light, which looks a bit like the following picture:

The part I circled represents a pixel, and each pixel is composed of a red bar, a green bar, and a blue bar. Therefore, the smallest point we can see on the screen is not actually a pixel, but the three "color bars" that make up the pixel.

Of course, we can't see these small color bars with our naked eyes. The resolution of modern computer screens is very high, and if we want to see it, we must use some kind of magnifying glass.

Each small color bar only emits light of its own color, so the question becomes, how do our eyes see other colors through these three colors of light?

In fact, the answer is very simple. It is a visual illusion. Other animals do not have the same visual illusion as us, so the colors constructed on our computer screens are ineffective for them.

But to understand why we experience this optical illusion, we have to start with how our eyes see color.

How does the human eye see color?

As we all know, the colors or visible light seen by the human eye are part of the electromagnetic wave, and the electromagnetic wave is a continuous range of wavelengths. From radio waves to microwaves, to X-rays and gamma rays, they are all part of the electromagnetic spectrum, but their wavelengths are different.

The wavelength of electromagnetic waves that the human eye can detect is approximately between 400 nanometers and 800 nanometers. The part above is called infrared, and the part below is ultraviolet. Both are wavelength ranges that we cannot see.

Light can be a mix of any of these wavelengths, but no matter how the mix is, when it interacts with matter, some wavelengths of light are absorbed while others are not. The light that is not absorbed is reflected, and the visible part of light that enters our eyes is what we perceive as color.

Hundreds of years ago, the great physicist Newton observed this and said that color is not intrinsic to an object but is the result of the light it reflects.

The place where we perceive light is our retina, where there are two main types of photoreceptor cells, rods and cones, which convert light stimuli into electrical signals and interact with the brain.

Rods can detect most wavelengths of visible light, but they cannot distinguish between them, so these cells are generally responsible for our perception of brightness.

Image source: che

Since rods are mainly distributed at the edge of the retina, you will find that your peripheral vision is less colorful when you look straight ahead. In addition, since we have a relatively high ratio of rods (about 120 million, while there are only about 6 million cones), you can see things in dim light at night, but it is difficult to distinguish colors.

When we look ahead, we may see something like this, Image source: cambri

On the other side are the cones, which are responsible for color.

However, our eyes cannot distinguish visible light wavelengths as clearly as our ears can. While our ears can identify individual notes, sounds and instruments, our eyes can usually only detect three wavelength ranges: one for red light, one for blue light and one for green light, which are handled by three different types of cones.

Note that different cones sense a range of wavelengths, not just one specific wavelength, because each cone is activated by a range of wavelengths of light.

Because the three types of cones detect a range, these cells cannot distinguish the difference between two wavelengths within that range, nor can they distinguish the difference between monochromatic light and mixed wavelength light within that range.

In fact, the rich colors we can perceive are constructed by our brain after analyzing the input from the three types of cone cells. Since each cone cell is activated by 100 wavelengths, many people believe that our eyes can see 1 million colors - all combinations of the activation of the three types of cone cells.

Because of this, we can reconstruct most of the colors we see using just three colors.

It is important to mention here that the combination of the three colors can display far less colors than the eyes can distinguish, but it is basically enough.

Many people believe that pink is a non-existent color because there is no wavelength that shows this color. It is an illusion constructed by our brain based on red, green and blue.

In fact, it is not difficult to find out from our perception of color that our brain can construct most colors, not just pink, and this is what our computer screens do.

Finally: What do animals see when they look at the screen?

Since computer screens are just a visual illusion based on human cones, they cannot be shared with other animals, because the spectral characteristics of cones in different animals are basically different, and even the types and numbers of cones are different.

For example, most mammals actually only have two types of cones - blue cones and green cones (among mammals, human eyes are definitely powerful), most birds have four, and mantis shrimp have as many as 16.

If we show different animals our computer screens, they can only see the appearance of the objects.

In terms of color, they are not only very different from what we see, but also very different from the real objects they normally see.

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