BASIC COLOR PRINCIPLES
[1] Light and color (color?s true identity)
1. The characteristics of color
Visible light, like radio waves, gamma rays, X-rays, infrared rays, and
ultraviolet rays, are electromagnetic waves. These electromagnetic
waves have been found to possess both the propagation properties of
waves and of particles.
When an object is heated to a high enough temperature, the electrons
within that object begin to oscillate at a high frequency and emit
2. Construction of the human eye
electromagnetic waves (or light). The higher the temperature, the higher
The retina of the human eye contains two types of light-sensitive cells:
the frequency of the oscillation and the shorter the wavelength of the
rods and cones. There are three types of cones, each sensitive to a
resulting light. Similarly, the lower the temperature, the longer the
different wavelength of light. Thus, depending on the amount of light
wavelength. Light, however, is not characterized by the oscillating
detected by each cone, you perceive many different colors. These
frequency, but by the wavelength of the electromagnetic wave.
cones are concentrated in the center of the retina, making your eyes
A normal human eye is able to detect electromagnetic waves ofmost sensitive to light that enters from the direct front. Under these
wavelengths between 380 and 780 nm, and light within this condirange itions, sit is said that each cone can distinguish up to 200 different
called "visible light."levels. Rods, on the other hand, cannot distinguish between different
colors, but are very sensitive to different degrees of lightness and
Light of a wavelength just below 380 nm is called ultraviolet light, and
darkness and can detect even a small amount of light.
that of a wavelength just above 780 nm is called infrared light. Since
both lie outside of the range from 380 to 780 nm, both cannot be The amount of seenlight that enters the eye is adjusted by the iris, the
by the human eye.membrane that surrounds the pupil and adjusts the size of it.
The human eye perceives light of different frequencies as different
colors. Visible light with longer wavelengths are perceived as reddish,
and visible light with shorter wavelengths are perceived as bluish.
Within the visible light spectrum, lie red, orange, yellow, green, purple,
and an infinite number of shades between. Within white light (natural
light or sunlight), all these colors exist. This can be shown by shining
white light (natural light or sunlight) through a prism and observing how
the refraction of the light through the prism separates the light into its
different components. Thus, the spectrum of white light is seen broken
down into its different color components in order from longer
wavelengths to shorter ones.
3. Color temperature
A theoretical black body will emit electromagnetic radiation depending on
its temperature. As the temperature rises, the emitted radiation will change
from black to copper, red, orange, yellow, white, and finally blue. The
temperature at the time a color is emitted is considered the temperature of
that color. When observing photography or judging colors, the
temperature of the light source is considered a controlling factor.
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ACEC
