Color is sensed when white light bounces off an object and is reflected into the eye. Objects appear different colors depending on what colors were absorbed and which were reflected. Color is “seen” by the rods and cones in the eye. Cones detect color and rods detect black, white, and shades of gray. People who cannot see colors properly are colorblind. There are many different kinds of colors and they are classified in many different ways (The World Book Encyclopedia p 818, 819).
The eye consists of many parts. The part of the eye you can see when you look at someone consists of four parts. The colored part of the eye where the light enters is called the iris. The white part around the iris is the conjunctiva and episclera. This part also contains blood vessels. The cornea is the clear covering of the iris and pupil. The cornea contains no blood vessels. The lens is located behind the iris. The lens is used to focus, as in the cornea, but the lens can move. The retina is responsible for telling the brain what a person is seeing. They determine all the different parts of what is being seen. It then codes them to electrical signals for the brain (Cassel p 4-10).
Rods and cones are in the retina. There are three kinds of cones. Each cone can sense a different color. Rods are used when a person is in dim light (Hubel p 162). The optic nerve is what sends all these messages to the brain (Cassel p 261).
Sometimes people have difficulty telling colors apart. This is called colorblindness (Webster’s Dictionary, p 281). Sometimes colorblindness is hereditary. Other times there is a problem with the message reception from the optic nerve. Another problem can lie in the retina. People can have trouble recognizing colors because of certain drugs.
People are diagnosed as being colorblind by taking tests. They look at different colored numbers that are in order by their color. This way they can be diagnosed as being colorblind in certain areas (Cassel p 52). A person can have different extents of colorblindness depending on what the problem is. A person can be colorblind because they have too few of a certain kind of cones or because they have too many. The more problems a person has, the more colorblind they will be (Hubel p. 172).
Color perception varies from place to place. Some cultures have only a few colors that are distinguished from one another. Some cultures do not separate green from blue and yellow from orange. Other cultures have more specific names for things that are important to them. Eskimos have seventeen words for white because of all the snow.
What cultures think about colors also varies. In America, the color black is usually perceived to be bad. Other cultures have white meaning bad. Sometimes, colors are perceived differently by what they are associated with. Things like apples are usually red, bananas are usually yellow, and oranges are orange. If these colors were slightly off color
a person probably would not notice because they know what that color should be.
Say there was a banana, and it was more yellow-green than yellow. Most people would not think anything of it. If there was an area of yellow-green color on a piece of paper and a person was to identify it, they would most likely notice that it was not yellow.
Color can show things about people. People with similar personalities tend look at colors in a similar way. Psychologists also use color as a form of therapy.
Colors considered to be warm and cold can have a psychological effect on what a person thinks about his or her temperature. If someone was in a cool red room they might not notice they were cold. If they were in a cold room filled with blues and greens they would be more likely to realize that the temperature was down in the room http://www.eb.com/180:/cgi-bin/g?DocF=macro/5001/41/14.html;bold=on;w=, accessed January 25, 1999).
The Munsell Color System is used to determine color. It begins with the hue. Hues are created when the wavelength is shorter or longer. The colors begin with red, the longest. Progressing from longest to shortest, the following hues are red-orange, orange, yellow-orange, yellow, yellow-green, green, blue-green, blue, blue purple, purple, and red-purple.
After the hue is chosen, the chroma is determined. The chroma is how much of the original color is contained in that color. The more color it contains the darker a color will be. Now this new color is moved either toward the black or the white. This is called the value of a color. If the color is moved toward white, white is added to the color. The chroma does not change, so changing the color of a dark chroma won’t produce a light chroma.
Another way of categorizing colors is by using the color triangle. The color triangle has black and white at two points and a color at the other. When the color is mixed with white, a tint is formed. When the color is mixed with gray, a shade is formed.
There are many different kinds of colors. They vary depending on whether a person is referring to paint or light. The primary colors of paint are red, yellow, and blue. This means mixing colors cannot form them. The primary colors of light are red, green, and blue.
Mixing two primary colors in paint forms a secondary color. Red and yellow mix to form orange, yellow and blue mix for green, and blue and red form purple. Mixing two primary colors in light form purple, blue-green, and yellow. That is why we say white light is a mixture of all colors.
Complementary colors in light are across from each other on the color wheel. Orange is a complement of blue, purple is a complement of yellow, and green is a complement of red.
The last kind of color is an intermediate color. Intermediate colors are formed when a primary color and an intermediate color are mixed. Intermediate colors include red-orange, yellow-orange, yellow-green, blue-green, blue-purple, and red-purple (The World Book Encyclopedia p 821, 822, 823, 825).
The colors on a monitor are formed by the three primary colors of light: red, green, and blue (RGB) (http://exchange.coa.edu/HEJourney/polcom/colort.html, December 14, 1998). This is also how a color television works. When the electrons meet the television they make the pieces red, green, or blue. They are so small and close together that they appear as different colors (World Book Encyclopedia p 121, 123).
The same color can appear different depending on what the surrounding colors are. Two complementary colors will appear contrasting (Tritten p C43). A color will appear lighter against a lighter background. That same color will appear darker against a dark background. Sometimes colors are so similar they create the illusion of a third color. This is called visual mixing.
An afterimage is created when you look at an object for a long period of time. When you look at something light or white the colors will appear reversed. Red becomes green, and yellow becomes blue (The World Book Encyclopedia p 820, 819). A quote about afterimages was given by Johannes Ilten: “It has been psychologically proven that the afterimage as well as the simultaneous effect show the strange and so far inexplicable fact that our eye demands for a given color it’s complementary completing and produces it on it’s own if it is not provided” (Tritten p C43).
Color is a product of many different things. We physically see color by the light hitting the retina and being absorbed by the rods and cones. Colors are distinguished by sorting them into categories. These could include tint, shade, tone, chroma, value, or hue. It could also be determined by whether a color is primary, secondary, intermediate, or complementary. The illusion of different colors can be created by the colors around a color or placing bits of color very close together as in a television. Afterimages create the opposite of colors. All color is a product of light. Without light, we would only be able to see in black and white (The World Book Encyclopedia p 818, 819, 822, 823).