Color

Light is part of the electromagnetic spectrum. The human eye is only able to detect a very small fraction of these wavelengths. This is called the visible light spectrum. 

When light is directed into a prism, white light becomes separated into the colors humans can see – red, orange, yellow, green, blue, indigo, and violet. Rainbows are created the same way when white sunlight is dispersed through water drops in the sky.

Nature has evolved to take advantage of the heat absorption/reflection that occurs through the absorption of colors. Many desert animals, like the Scimitar Oryx has white fur which has evolved to reflect heat away from the body. 

The human eye is designed to see color using photoreceptor cells called cones. Cones need light in order to work well, preferably normal or bright light. When all the cones work together properly, they sense the combinations of light waves so that we can see millions of colors!

When light hits an object, some wavelengths are absorbed and turned into heat and other wavelengths are reflected. The reflected wavelengths are what we perceive as color. 

The retina contains the photoreceptor cells which are designed to detect light, darkness, and some color wavelengths. There are actually over 120 million photoreceptor cells in each of your retinas!

The red cones are activated by the red wavelength reflecting off the apple. These cones transmit this information from the retina in the eye to the brain via the optic nerve.

All color perceived by humans is a combination of 3 colors detected by photoreceptor cones located in the retina, inside of the eye. Since other species have different sets of photoreceptors, they therefore see the world and its colors very differently. 

Dogs only have 2 cones: blue and yellow. Therefore they cannot see red and green objects. So a red ball in green grass will be almost impossible for a dog to see.

Butterflies have 5 sets of cones, including colors humans are familiar with: red, green, and blue. Humans are unable to process what the other 2 cones detect. In addition butterflies can also see ultraviolet light which helps them in their search for pollen.

Currently there are 2 scientific theories which attempt to explain why the human race evolved to see colors only on the red, green, blue spectrum. Other species in the animal kingdom evolved to see different colors, depending on that species’ individual needs. 

New scientific theory suggests that the ability to see red in particular may also be important in recognizing sickness in other humans, as well as helping with communication. Sick humans can look flushed and blushing can indicate excitement, embarrassment, or fear. 

Butterflies can see ultraviolet light, which helps them find pollen-rich flowers. Some flowers in turn have evolved to have ultraviolet “pollen guides,” bright patches of pollen that reflect ultraviolet light and attract pollinators like butterflies.  

An eagle has 5 photoreceptor cone cells and can also see ultraviolet light. The ultraviolet light evolved to help the eagle find food by following the urine trails of small prey.

Additive color mixing is used to make the colors displayed on computer screens. Additive color mixing begins with a black background and uses the colors red, blue, and green. When all colors are combined, white light is produced, giving a full color image.

Within any given subject or field, there are a specific set of terms used to describe processes or objects. People who use color extensively such as graphic designers, artists, printers, and painters have their own set of terminology to describe color.

Each of the 12 colors can be changed using one of 3 processes: tinting, shading, or toning. Tinting occurs when white is added to any of the 12 colors. For example, white can be added to red to make pink.

A tone is created by adding gray (both black and white) to one of the 12 colors on the color wheel. It’s common for artists to mix a little gray into their paints to adjust the intensity of their pigment colors.