How Does HUMAN VISION Work? | Illustrated


Is it possible for two people to see the exact
same object as completely different colors? Before we answer this question, we need to
know how vision works. When light, usually from the sun, hits an
object, the chemical makeup of the object allows it to absorb some colors and reflect
the rest. Part of the Electromagnetic Spectrum, the
visible spectrum consists of all colors, ranging from ultraviolet to infrared, which an object
absorbs all the colors of except for those it reflects. A full spectrum of colors makes white, and
so something that reflects white reflects almost a full spectrum of colors while black
objects absorb all colors and reflect almost none. This explains why powdered glass looks white;
its increased surface area allows it to reflect more light as opposed to a larger, clear chunk
of glass that reflects some light but allows most to go through. Thus, whatever object light hits absorbs some
colors and reflects the rest, so whatever your eyes are staring at see the reflected
colors. When light hits a red object, for instance,
it absorbs all colors except for red, which it reflects. The red photons go through your eyes and hit
your retinas, which contain rod and cone cells. Cone cells can detect three types of light:
cyanolabe, chlorolabe, and erythrolabe, which together make up all the colors you see. The colors that these cone cells detect travel
along the optic nerve to the visual cortex, a huge part of your brain dedicated to vision. Some animals with even better vision than
humans, such as bald eagles, have advanced retinas and visual cortices that can detect
an ant on the ground from a 10-story building! Under moderate light and over, cone cells
are predominantly used for vision and under low light, rod cells are used. This is because of the retinaldehydes that
make rod and cone cells operate. Retinaldehydes are broken down by light rays,
and retinaldehydes are regenerated much faster in cone cells than in rod cells. Under lit circumstances, therefore, the faster-regenerating
retinaldehydes in cone cells outcompete the slower-regenerating retinaldehydes in rod
cells, and you only use cone cells in brighter light. However, under low light conditions, the retinaldehydes
in rod cells are no longer being broken down. Since there are many more rod cells than cone
cells, the rod cells have free reign to slowly regenerate, taking over in low-light environments. This is why when light is suddenly removed,
you cannot see for a short while; the retinaldehydes in the rod cells that were being broken down
by the light take some time to regenerate to the point where you can see. Rod cells can detect light much better than
cone cells but cannot detect color. A condition known as color blindness involves
the inability to produce one or more of the three cone-cell pigments that allow for color
vision, or involves the correct synthesis of the pigments but an inability to perceive
light correctly with one or more of the three cone cell types. You can picture this disorder as a printer
without one type of ink; the printer will print images with all colors except the one
that is missing. In the same way, people who are color-blind
cannot correctly perceive the colors that involve the color of the pigment they are
missing , such as in this image, where people having a deficiency in the green chlorolabe
pigment will not be able to see the number 8. And now comes the answer to the question of
“Is your red the same as mine?” If you do not have a deficiency in one of
the three color types of cone cells, you most likely perceive the same type of colors as
others without color blindness, however, the perceived colors could be slightly different
in shades due to small differences in each individual. So next time someone says something is a specific
color, keep in mind that everyone’s perception of color is not exactly the same.

3 comments

  1. soo now what i did understand that alot of normal ppl can see diffrent colors but not that much diffrent right? and that most of the ppl see the same color

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