Primary Colors
In the world of art and oil painting, the three primary colors are red, yellow, and blue. The artist can mix combinations
of these three primary colors with white and black to create all the colors on the palate. Because these color mixtures are
subtractive, it is necessary to blend them with white to create lighter tints. White itself must be a separate pigment and
cannot be created by mixing red, yellow, and blue. In particular, the secondary colors, orange, green, and purple, are each
created as equal mixtures of two primary colors. With these mixtures, orange = red + yellow, green = yellow + blue,
and purple = red + blue. When the primary and secondary colors are arranged on a circle (the “color wheel”), the complementary
colors red/green, orange/blue, and yellow/purple, appear in opposite positions on the wheel.
In natural light, the colors of the spectrum (the rainbow colors) are infrared, red, orange, yellow, green, aqua, blue, violet,
and ultra-violet. The extreme colors infrared and ultra-violet are not visible to the human eye. In human vision,
the retina of the eye contains three types of color-receptor cells called “cones”. The three categories of cones are primarily
sensitive to the colors red, green, and blue. The eye then sees all other colors as combinations of these primary three.
As a result, even though the pure spectral colors orange, yellow, aqua, and violet, are not themselves color mixtures,
the eye perceives them as though they were combinations of primary red, green, and blue. Even violet, on the end of the spectrum,
looks similar to a mixture of red and blue.
Because of the arrangement of human vision’s primary color receptors, it is possible to use mixtures of primary colors in video
monitors, color TVs, and printing devices to simulate other colors. In video and photography, the primary colors are,
like the eye’s cone cells, red, green, and blue. These primary colors are additive, so each color shown by a video monitor
or TV can be displayed as one of their combinations. White is shown as an equal mixture of all three. The secondary colors cyan,
magenta, and yellow, are equal combinations of blue + green, red + blue, and red + green. The secondary magenta resembles the natural
color violet to the eye. In color printing, mixtures of ink are subtractive, so printers are able to mix the secondary colors
along with black, to approximate the remaining colors in the field of vision.
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