We highlight the similarities in the functioning of the human eye and that of a digital camera. The reality is that there are many more disparities because the eye is a complex and almost perfect organ. However, the operation of digital cameras has some similarities in relation to our eyes that we want to highlight.
Despite the substantial differences, the human eye and digital cameras share a number of elements with very similar functionality.
If we have to be honest, despite the great similarities of the human eye to a digital camera, in terms of operation, the reality is that there are many more differences than similarities. On the basis that the human organ of vision and photographic cameras are very different systems and that the precision of the eye can never be achieved by a technological device, we can establish some similarities that may be surprising.
How were digital cameras born?
The truth is that today’s digital cameras were created from the idea of the camera obscura that Leonardo Da Vinci established in the 15th century. And it is that to manufacture the technology of the cameras, the physical bases of this Da Vinci invention have been followed.
A camera obscura is based on a dark room that has a small hole in a wall. This makes the image being generated outside the room visible inside the room.
Keep in mind that the light conditions outside the camera obscura make this possible. This concept of the inventor is essential to explain processes such as the operation of human vision and even the mechanics of the digital camera.
As we have already said, the human eye is practically perfect, and we could never put it at the level of a digital camera since the procedures that they follow to generate images are not similar. However, there are some similarities that we can highlight.
Similarities between the human eye and the digital camera
The processor in a camera will be like our brain. The basis of their similarities is actually in the operation of both. The eye receives rays that pierce through the pupil to cross the lens and reach the retina. This light is transformed into electrical signals because of the photosensitive cells of the retina and is sent right to the brain.
Because of its part, a photographic camera also receives a light that passes through the diaphragm of these devices, to pass through all of the crystals that define the lens and, thus, reach the CCD (where the precise image is formed), that may send to the processor. The processor in a camera will be like our brain.
Both the human eye and cameras use the physical properties of light to modify its behavior.
IRIS / DIAPHRAGM
The iris is the element that is basically responsible for regulating the amount of light that enters the eye so that we can see correctly. In photopic (high-light) conditions, the iris contracts reducing the amount of light reaching the retina. In contrast, under scotopic (low light) conditions, the opposite effect occurs when the iris relaxes.
The diaphragm in still cameras regulates the amount of light that reaches the CCD sensor and allows you to control the depth of field.
The simile with the photographic camera is found in the diaphragm, which in this case is the element in charge, among other things, of regulating the amount of light that reaches the CCD sensor or the photographic film.
RETINA / CCD SENSOR
The element that lights reach in the eye is the retina. In it, the photoreceptor cells are responsible for converting light into electrical signals that are sent to the brain through the optic nerve. Its photographic counterpart today may be the CCD sensor and before, the photographic film or photo reel.
RETINA / ISO SENSITIVITY
The retina contains the photoreceptor cells of the eye (rods and cones) and acts as the CCD sensor or photographic film of the camera when it comes to receiving information in the form of light and converting it into electrical pulses that will be interpreted by the brain/processor.
One of the characteristics of the retina is its ability to increase or decrease its sensitivity to light, its adaptability. In this sense, the eye increases its sensitivity to light when it is in dark environments and reduces it when there is plenty of light. The camera, for its part, has the ISO sensitivity factor, which formerly referred to the light sensitivity of the film and which currently speaks of the level of amplification of the signal received by the CCD sensor.
LENS / FOCUS SYSTEM
In both cases, both the complex ocular system and the camera, a system is necessary that allows us to modify the focus of the objects depending on the distance at which they are (near, intermediate, or distant vision). The eye relies on the lens and the ciliary muscles to carry out this function called accommodation, which in the case of the photographic camera is carried out by means of a lens system.
The presbyopia or eyestrain amounts to a focusing system and a broken camera can only correctly focus on distant objects.
Peculiarities of Human Vision
First of all, we must bear in mind that the human eye does not have a fixed vision, so we could more closely resemble that of video cameras. In addition, the resolution of our eye is very difficult to calculate, since it is highly variable depending on various parameters, such as inclination.
However, some calculations estimate that the resolution figure of human vision could approach 576 megapixels.
Another difference between the human eye and still cameras lies in the dynamic range. A camera is much more static and offers us a single type of exposure for a specific area. However, our eye evaluates an entire scene to select the most suitable light.
At this point, the so-called rods come into operation, visual cells whose function is to adapt the sight to the established light conditions. This makes it clear that the dynamic range of the human eye is much higher than that of any device.
The manufacturers of the cameras established the focal length according to some parameters related to the own length of the human eye. Although, obviously, the area of vision of a person can reach 180 degrees. This is how wide-angle lenses came to be.
The problem is that the length is not exact in the human eye, since it depends on various factors. Something to keep in mind is also that the eye is a curved organ, however, the CCD of a camera is flat, which indicates that it can never infinitely resemble human vision.