The human eye is an analogue structure and it cannot be precisely measured by a pixel size, which is a digital term. The visual cortex in the brain cannot perceive the light-based information, transmitted from the eyes as a screen. It interprets the light-based information and generates an image. This image is refreshed depending on the speed of the nerve cells (i.e neurons) that extend from the eye to the brain.
For example, if we consider this as a FPS (Frame – per – Second) value, 30 FPS in a video clip will be enough for our eyes to fluently perceive the images. However, that does not mean that the human eye have a 30 FPS value. Human eye also have a certain threshold value and when looking at an object, moving faster than that value, it cannot register any movement and sees it, as there is no movement at all. On the other hand, by using specialized cameras with high-speed capture ability, the movements of a speeding bullet can be analyzed in millisecond levels.
We can conduct a simple test for the human eye speed. First of all, set the vertical scanning frequency for your desktop CRT monitor to 60 Hz. (for this, right click on the desktop>settings >advanced>monitor.) After setting it to 60 Hz, focus on an object on the side of the monitor while looking at the monitor from a distance of 30 cm but also keep looking at the monitor as well. You will see how the screen refreshing, which you never feel when looking at a screen in a normal way, occurs from top to bottom in a scanning manner. If you notice 60Hz scanning while looking at the screen normally, try this method at 75 Hz. I can personally track the refreshing rate up to 75 Hz. but at 85Hz and beyond, I fail to register the page refreshing. The speed of the eye may vary from person to person. People, who constantly track the moving objects with details and who work in jobs that require high level of attention and focus, may have faster eye reflexes as well.
The retina, where the light receptors of the eye are located, is a membrane, comprised of neural constructs. The light receptors in the retina have a measurable size just like the receivers of the digital cameras. And the hollow section of the retina (fovea) has more of those receptors than the other regions. The light, arrive on the retina is transmitted to the brain in a compressed state. That is why, sometimes our eyes play games with us and we see objects not exactly, as they are. As long the number of light receptor cells (or you may call it megapixels) in our eyes is above a critical value, the quality of our visions remains unaffected. Because the images are completed by the brain. In addition, even if we lose one of our eyes, the imaging resolution would not drop; only the sense of depth may be impaired a little. Even in the cases that are known as the “retinal detachment”, where most of the light receptor cells in our eye are destroyed, we see the image partially. We can liken this to the following; you cover half of the objective of the camera on your hand but you still see the image on the visor fully. Because the processor of the camera completes the missing part.
In order to express the visual perception capacity of the eye as megapixels, you need to think of the receptors in the eyes as pixels and you need to test at what level of details the brain can generate a scene. The human eye is a small organ but it does the job with a little amount of light that it receives. On the other hand, the lenses of high-megapixel cameras are very large and they see much more illuminated areas in a darkened image compared to the human eye. Ultimately, it is safe to say that if you take an objective with the size of a human eye and take a picture with the highest possible megapixel setting and if we compare what a human eye can see at the same scene, the human eye would register and define more details. If the picture, taken by the digital machine is displayed and analyzed without zooming with the same terms as the human eye, t will be seen that the objective would catch fewer details.
What Is The Resolution Of The Eye?
That is why the human eye is a perfectly created organ that cannot be compared to the imaging power of the artificial lenses. However, they can be expressed with megapixel count, which is a digital data. If the calculation for this is performed under the conditions that I underlined above, an approximate value can be stipulated. However, we should not forget that the term “megapixel” is nothing more than a term that indicates with how many pixels an image, taken from a scene is displayed. Of course the image will be displayed in more details if the megapixel count is high but in order to compare it with the ratio that corresponds to the human eye, the subject should be regarded as a scientific research material and should be analyzed under lab conditions with tests.