The different colors which we see are actually just mixtures
of a few colors. Colors can be mixed by addition (which involves
the primary colors) or by subtraction (which involves the secondary
colors). The concept of color addition and subtraction may be difficult
to understand because it conflicts with experience from paints.
Therefore it is important to keep in mind that the colors we talk
about in physics are of a pure form whereas the paints which we
use in the real world are not pure.
The primary colors used in color addition are Red, Green,
and Blue. The combination of the primary colors forms white. The
color white is seen when an object reflects all color. Red and
Green mix to form yellow, Green and Blue mix to form Cyan, and Red
and Blue mix to form Magenta. The colors formed from the primary
colors are known as the Secondary colors.
The color television uses the concept of color addition.
The television has millions of tiny little dots, called pixels.
Colors are seen when electron beams shine on these pixels, causing
them to glow either red, green, or blue. We see different colors
on the screen depending on how the various amounts of the colored
pixels are adding together.
The secondary colors are Cyan, Magenta, and Yellow. When
these three are mixed together, they form black. Color by subtraction
involves the absorption of some colors and the reflection of the
colors which weren’t absorbed. The colors that are reflected, are
the ones which we see.
Colors can be absorbed through the use
of such things as dyes, pigments, or filters. The color of the
clothes that we wear is seen because of color subtraction. For
example, if your friend is wearing a yellow shirt, you see it as
yellow because of color subtraction. The white light hits the shirt,
and the dye of the shirt absorbs the blue part of the spectrum and
reflects the red and green. You then add the red and green together
and see the color yellow.