Very often photographers, and sometimes people from other specialties, are interested in their own eyesight.
The question seems to be simple at first glance... you can google it, and everything will become clear. But almost all the articles in the network give or "cosmic" numbers - like 400-600 megapixels (MP), or it's just some strange reasoning.
Therefore, I will try to briefly but consistently, so that no one misses anything, to disclose this topic.
Let's start with the general structure of the visual system:
Retina
The optic nerve
Thalamus (LCT)
Visual cortex.
The retina consists of three types of receptors: sticks, cones, photoreceptors (ipRGC).
We are only interested in cones and sticks, as they create a picture.
Balls perceive blue, green, red color.
Sticks form a brightness component with the highest sensitivity in the turquoise color.
Kolobochek average 7 million, and sticks - about 120 million.
Almost all the cones are located in the central FOVEA hole (yellow spot in the center of the retina). It is fovea that is responsible for the clearest area of the visual field.
For better understanding, fovea covers the nail on the little finger on the outstretched arm, allowing an angle of about 1.5 degrees. The further from the center of the fovea, the more blurry the picture we see.
The sticks are responsible for the brightness/contrast perception. The highest density of sticks is approximately in the middle between the central hole and the edge of the retina.
It is an interesting fact - many of you noticed the flickering of old monitors and TV sets when you look at them with "lateral vision", and when you look directly, everything was fine, right?
This is due to the highest density of sticks in the side of the retina. The clarity of vision there lousy, but the sensitivity to changes in brightness - the highest.
Just this feature helped our ancestors to react quickly to the smallest movements on the periphery of vision so that tigers do not bite their asses off.
So, what we have - the retina contains a total of about 130 MP. Yay, that's the answer!
No... it's just the beginning and the number is far from the right value. Let's go back to the central fovea hole.
The cones in the central part of the hole "umbo" have their own axon (nerve fiber).
These receptors are of the highest priority - the signal from them directly enters the visual cortex of the brain.
The cones, which are further away from the center, are already being assembled into groups of several, called "receptive fields".
For example, 5 cones are connected to one axon, and then the signal goes through the optic nerve in the cortex.
Sticks, in turn, are collected in groups of several thousand - for them, it is important not to sharpen the picture, but the brightness.
An intermediate conclusion: Each cone in the center of the retina has its own axon, cones on the borders of the central hole are collected in the receptive fields in several pieces, a few thousand sticks connected to one axon.
Here begins the most interesting thing - 130 million receptors are transformed by the grouping of 1 million nerve fibers (axons).
Yes, only one million!But how so?!
In cameras of a matrix on 100500 megapixels, and our eyes anyway are cooler!
So, 130 megapixels turned into 1 megapixel, and every day we look at the world around us... good graphics, right?)
There are a couple of tools that help us to see the world around us almost always clear:
1. Our eyes make micro- and macro-saccades - something like constant movements of the gaze.
Microsaccades are arbitrary movements of the eyes when one considers something. At this time, there is a "buffering" or fusion of neighboring images, so the world around us seems clear.
Microsaccades are involuntary, very fast and small (a few angular minutes) movements.
They are necessary for the receptors of the retina to have time to force new visual pigments, otherwise, the field of vision will simply be gray.