The Human Eye and Digital Camera (1)
Eye are accustomed to reading about the rapid progress of digital cameras, with more and more mega pixels, anti-vibration systems, technologies, more accurate auto focus and a host of increasingly sophisticated technologies, we can have the feeling that they are prodigious machines. However, the camera perfect sophisticated and still the eye . And let’s see why.
The Human Eye: An Incredible Machine
First, it should be noted that the functioning of the human eye rests on the most sophisticated and powerful computer that exists on our planet: the brain . What we see is the result of what has caught the eye with what the brain has processed. The analogy in digital photography-relatively speaking-would capture raw (RAW file or data captured by the CCD) and processed image (in Photoshop or JPG file that the camera has been generated from data raw).
Example of this teamwork of the eye and the brain is the fact that the human eye actually sees the world upside down and reversed as in a mirror (like a camera optical bench). It is the brain that is responsible for correcting the image in the two axes. In fact, babies see the world uncorrected (this the the reason why they often look in the opposite direction to the movement trying to follow).
Another example is what happens in Architectural Photography : If you tilt the camera up to photograph a tall building, the vertical lines converge. And the same thing happens to the human eye, only that the brain is responsible for correcting the distortion.
Continuing Vision
What we see is actually a constant flow of changing information that the brain is constantly processing, assembling images to generate a vision of the world around us. It is a very complex and surprising.
For example, although the joint vision of both eyes produces an angular field of about 130 °, in reality the area in which at one time the eye is focusing is only 0.5 °. The rest of the image remains blurred (progressively as we approach the edges ). All this happens quickly and continuously and that is why we have the feeling that this is occurring (imagine a camera with a 90 ° angle covered but only 0.5 ° is focused!).
The Retina: Perfect Sensor
The retina contains about 7 million cones (capture the red, green and blue) and about 120 million rods (extremely sensitive to light level). The distribution of both types of receptors is not homogeneous, since the cones are located at the center of the retina. This implies that the edges of our field of view are always monochrome (including daylight). However, the rods are capable of detecting light levels as low as a single neuron (as a reference point, under normal light, our eyes can recognize about 3,000 neurons per second).
Many animals (especially birds) have a much higher number of cones than humans, allowing them to detect prey at great distances. In contrast, nocturnal animals have a high number of rod to improve night vision.
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