Colors for health

• The eye:

Visual perception which is possible for humans only through the light, has been very well studied. It allows us to understand how the physical body transforms light and its components that are the colors into electrical signals, only signals that the brain can process.

Note that for bats and dolphins, the area is detected by the sounds with the sonar.

The eye allows us to see. But what is seeing?

All objects around us are illuminated by light. Intense on the day, low or very low at night, but the principle is the same.

Each object absorbs part of the light and reflects another. This reflected light is captured by the eye whose function is to transform the light into an electrical signal.

Each light beam passes through the cornea, is focused by the lens, sort magnifying glass, to arrive directly at the retina. The photoreceptor is at the level of the retina. It is a biological tissue composed of several layers of cells:

• Photo receptive cells whose function is to convert light into electrical signals
• transmission cells of these signals towards the optic nerve,
• nutritive cells,
• System regulation cells.

The optic nerve transfers the information in the form of electrical signals to the brain. It then "handles" these signals in various junctions by modifying them through other neural circuits from other body parts before sending them to the part of the cortex responsible for global integration, the area of vision.

This is to allow management of all information the same way that the brain only works with electrical signals.

Thus, the information coming from the eye are of the same nature as those from the ear, nose, skin, tongue, nose, and internal organs of thought.

It is the role of different sensory organs to transform a signal, light, sound, tactile, taste, smell, into an electrical signal.

This is what the eye does for light, just like a digital camera.

This is what the ear does for sound, just as a music recorder.

The evolution of cameras shows that there are different possibilities to transform light into an image: older devices using the chemical properties of light in an impressive photographic plate and a plastic, then paper. It required several operations to reveal the images by passing through several baths containing various chemicals: developer, rinse, fixer.

Today the light is directly converted into electrical signals that digitize the images. These are handled directly through the computer.

The eye has evolved, has become more complex during evolution in order to become more efficient. It has permitted the enabling of black and white, night vision, and eventually color vision.

It developed and two kinds of cells: rods for black and white vision and cones for color vision.

These cones are themselves divided by specializing, some to "see" red, others green and the others blue. Each category has the property of filtering in all frequency separated into three, according to their wavelength. The greatest wavelenghts perceived by the cones are specialized in red,  the mid lenght green and the short wavelenghts the blues.

The bandwidths of the cones are not defined rigorous ways. There are overlaps between red and green and between green and blue. So that  cones specialized in green receive more information than others: color vision is clearer, more precise in green colors