Red, Green and Blue are primary
colors as they cannot be obtained by mixing any color in any
proportion. But they can generate all the colors known to
us by combining in different intensities.
On combining in equal ratios primary colors give different
colors. Green and Red combine in equal proportions to form
Yellow colored light. Blue and Red combine in equal proportions
to form Magenta colored light. Green and Blue combine in equal
proportions to form Cyan colored light.
Yellow, Cyan and Magenta are three secondary colors. When
light of these primary colors is added together in equal intensities,
the sensation of white light is produced. The shade of a secondary
color obtained depends upon the intensity of light of primary
If Red & Green of equal intensities are mixed give Yellow
but if Red component is more then Orange shade (i.e. more
of Red side).
In mixing of primary colors all the colors add to give a
new color, hence this process of combining of light colors
is called an Additive Process.