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The splitting of white light into its components to produce color can be achieved with a variety of materials, one being a prism.
|Violet||668–789 THz||380–450 nm|
|Blue||631–668 THz||450–475 nm|
|Cyan||606–630 THz||476–495 nm|
|Green||526–606 THz||495–570 nm|
|Yellow||508–526 tHz||570–590 nm|
|Orange||484–508 THz||590–620 nm|
|Red||400–484 THz||620–750 nm|
Color is a visual sensation that results from the splitting of white light into its component wavelengths. Wavelengths are measured in nanometers (nm). Table 1 shows the different colors and their corresponding frequencies and wavelengths.
The splitting of white light into its components to produce color can be achieved with a variety of materials such as a prism, as shown in Figure 1. In a prism, blue light is refracted more than the red light because the refractive index of the glass is a function of the wavelength of the light.
Spectral color is the amount of light in each wavelength that is contained within white light. This is determined instrumentally by splitting light with a prism. This was first accomplished by Sir Isaac Newton in 1666. This is something that is constant, and it can be measured and quantified with electronic equipment such as a spectrophotometer.
Perceived color is the color that can be ascertained by the human eye and brain. There can be limitations to this, as the human eye contain three types of cones, each responsible for evaluating the visual stimuli for red (R), green (G) and blue (B) similar to the tiny chromaphores in older television picture tubes. These approximate 7 million cones are responsible for daylight vision. Additionally, there are around 120 million rods in the human eye responsible for night vision. The ability to visually evaluate the sensations of color varies from person to person, man to woman, young to old. Any abnormality in the rods or cones or the optic nerve that transmits the stimulus or message from the eye to the brain will impact perceived color, which is sometimes called “color blindness.”
Color is an important part of the cosmetic industry. Mankind has used colors on the skin since ancient times. The Ancient Egyptians wore distinct eye makeup, rouge and perfumed oils that softened the skin and prevented sunburn and wind damage. Not only did the men and women of Egypt wear makeup, but the statues of their gods and goddesses also were adorned with all these different types of cosmetics. The higher the status of the person, the more clothes and makeup they wore.