Graphics Programs Reference
In-Depth Information
light—red, green, and blue—are “mixed” together. You can mix color in two ways: sub-
tractive and additive. These color definitions are most often displayed in
color wheels
,
which equally space the primary colors around a ring and place the resultant colors when
primaries are mixed in between the appropriate primaries.
Knowing more about color will help you understand how your CG's color scheme will
work and help you design your shots with greater authority. (See the reading list at the
end of this chapter for some topics that expound on color theory and composition.)
SuBTRACTIVE AnD ADDITIVE COLOR
Subtractive color mixing is used when the image will be seen with an external light
source. It's based on the way reflected light creates color. Light rays bounce off colored
surfaces and are tinted by the different pigments on the surface. These pigments absorb
and reflect only certain frequencies of the light hitting them, in essence
subtracting
cer-
tain colors from the light before it gets to your eyes. Pile up enough different colors of
paint, and you get black; all the colors are absorbed by the pigment, and only black is
reflected.
When subtractive color mixing is used in painting, the traditional color wheel's pri-
mary colors are red, yellow, and blue. These three pigments can be mixed together to
form any other color pigment, and they form the basis for the color wheel most people
are exposed to in art education in primary school. In the world of print production,
however, a CMYK (Cyan, Magenta, Yellow, and blacK) color wheel is used. Cyan, yellow,
and magenta ink colors are the primary colors used to mix all the other ink colors for
print work.
Projected light is mixed as
additive color
. Each light's frequency adds on to another's
to form color. The additive primary colors are red, green, and blue. These three colors,
when mixed in certain ratios, form the entire range of color. When all are equally mixed
together, they form a white light.
A computer monitor uses only additive color, mixing each color with amounts of red,
green, and blue (RGB).
Warm colors
are those in the magenta to red to yellow range, and
cool colors
are those
in the green to cyan to blue range of the additive color wheel. Warm colors seem to
advance from the frame, and cool colors seem to recede into the frame.
HOW A COMPuTER DEFInES COLOR
Computers represent all information, including color, as sets of numeric values made up
of binary numbers—0s and 1s (bits). In an 8-bit color file, each pixel is represented by
three 8-bit values corresponding to the red, green, and blue channels of the image. An
8-bit binary number ranges from 0 to 255, so for each primary color you have 256 pos-
sible levels. With three channels, you have 256
×
256
×
256 (16.7 million) possible combi-
nations of each primary color mixed to form the final color.
