It is well known that humans win in the competition of nature in large part due to the brain, our brain only accounts for about 2.5% of the body weight, but it consumes about 25% of the body's oxygen, which means that the brain is our body's highest "energy consumption" organs.
What is surprising, however, is that about 65% of our brain power is used to process the information collected by our eyes, and if we compare the brain to the CPU of the human body, then our eyes take up 65% of its memory.
The reason why the eyes take up so much memory is actually just like some computer software - the more powerful the function the more memory it takes up.
So, just how powerful are our eyes?
Strange facts about eyes
It is no exaggeration to say that the human eye is the second most powerful organ in the human body - after the brain, part of which is reflected in the development of the eye, which ends at the size of the eye from the moment we are born.
To work with the powerful eye, the most powerful muscles in the body are those that move the eye, and these muscles have almost 100 times more control than other muscles.
We usually say that our eyes are tired and need to rest, in fact, our eyes never rest, no matter day or night, it is constantly working, it is only the muscles that need to rest.
There are many more "hardware facts" about the eye, but compared to its function, this hardware is worthless!
The primary function of the eye is imaging, which transmits information about the surrounding in the form of images to the brain, which then analyzes it and mobilizes the rest of the body to respond.
How is the eye imaged?
The imaging principle of the eye is somewhat like convex lens imaging, except that it is not simply a convex lens on one side, but a very complex system.
When light enters the eye, it is refracted and adjusted by a series of ocular structures, such as the cornea and lens, to eventually form an image on the retina.
This image, formed by the pooling of actual light, is called a real image, and one of its most important features is that the image is upside down, so our eyes are actually feeding our brain the upside down world.
The reason why we don't think we live in an upside down world is that our brains are adapted to this upside down. In fact, if we turn our heads upside down and look at the world, it will only take a few weeks for our brains to adapt to "looking at the world upside down".
Another major application of convex lens imaging is cameras, so people often compare their eyes to cameras.
Although the two are basically not comparable, we can simply do a pixel-by-pixel comparison (which may not be fair) in order to show the power of the eye.
The resolution of a digital image (Resolution - digital image resolution) is often expressed in terms of the number of pixels, for example, some cell phones nowadays can take an image with a resolution of 12032*9024, so this image is more than 100 million pixels (product), which means that the cell phone camera is 100 million pixels.
So how many pixels can the human eye "capture"?
According to the scientist and photographer - Roger Clark, PhD, the resolution of digital images of the human eye is 576 million pixels [1].
His algorithm is actually very simple. According to human eyesight, our eyes can distinguish 0.6 arc-minute intervals in good light, so he gives 0.3 arc-minute (0.3 vertically and also 0.3 horizontally) equivalent pixels.
Then, each human eye has a horizontal field of view angle between 120° and 180°, while the vertical field of view angle is around 60°, which means that we can take pictures with a minimum resolution of 120 * 120 * 60 * 60 with both eyes together.
And above we have got 0.3 cents per pixel, so the number of pixels "shot" by the two eyes is 120 * 120 * 60 * 60 / (0.3 * 0.3), which gives an answer of 576 million
We usually can often see the human eye to reach 576 million pixels is from this scientist's this data, but this answer is actually a lot of misleading.
Due to evolutionary limitations, although our eye sees widely, it can actually only notice details in the central part, while the surrounding details are actually only valid for moving objects.
The evolutionary explanation for this is that this evolution facilitates us to focus our attention on the center - generally on the prey, while the peripheral vision we are used to prevent predators such as lions from approaching us, so it does not need to be too clear, it is good to catch moving objects.
In foreign forums, there is a god according to the human eye to see the perspective of the production of a human eye "out" of the photo, it probably looks like this.
The image of our eyes becomes unclear after 20° from the center, so the pixels of our eyes are actually much lower than 576 million, only between about 5 and 15 million pixels.
Pixels don't tell us much, what matters is that our eyes can distinguish 0.6 arc-minute intervals; in addition we can distinguish about 500 shades of gray, whereas on some computer screens the RGB color model can only display 256 different shades of gray.
The miracle of two eyes working together
Although, our eyes are amazingly capable of imaging, it does not create a 3D image, the image captured by our eyes is also flat, or 2D.
There is no doubt that we are creatures living in a three-dimensional world, but it is true that our eyes, like the camera, can only show us two dimensions.
The reason why we can feel another dimension - "depth", in fact, or thanks to the brain, and the use of the two eyes together.
For many predators, their eyes are generally as long as humans in the front, this evolutionary direction is actually conducive to the creation of stereo vision, we can use such two eyes to transmit images to the brain at the same time to deduce the distance.
Since there is some distance between the eyes on the face, each retina produces a slightly different image, and the brain derives the "depth" based on this difference.
This stereo vision is most effective at distances up to 5 meters, beyond which our brain begins to use relative size and motion to determine "depth".
The eyes of most herbivores are on the sides, so many people now believe that herbivores have little ability to discern "depth," or at least to see the richness of the world as we do.
It is easy to see that many of the planets collected by the eye require "deep processing" by the brain, so it makes sense that it takes up "memory".
Finally
For animals, the evolution of the eye is a miracle, and Darwin, who wrote The Origin of Species, was also puzzled by the evolution of the eye and admitted that the idea that the human eye evolved through spontaneous mutation and natural selection was "absurd".
Of course, Darwin was just talking about how hard it is for the human eye to evolve, but nature is just so amazing!
Reference.
[1]Clarkvision.Notes on the Resolution and Other Details of the Human Eye（关于人眼的分辨率和其他细节）。
