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#EF
#T15,1,Chapter 3 Using Color Pg. 1
#HS,1,4,80,25,11,1
#C4,R5
~Y~I
~W~IDefining Some Terms~Y~I
To understand how to use color well, we've first got to get to know some of
the buzzwords.
#WN
~W~IAdditive Primary Colors ~Y~I- A painter mixes colors to produce new colors. The
basic colors that are added together to produce new colors are the primary
colors. The additive primary colors are ~R~Ired~Y~I, ~G~Igreen~Y~I, and ~C~Iblue~Y~I. If we want
~M~Imagenta~Y~I, we mix ~R~Ired~Y~I and ~C~Iblue~Y~I. If we want ~W~Iwhite~Y~I, we mix equal amounts of ~R~Ired~Y~I,
~G~Igreen~Y~I, and ~C~Iblue~Y~I. The color cube in Figure 3.1, which is on the next screen,
shows the additive primary colors.
#WN
%
#EF
#T15,1,Chapter 3 Using Color Pg. 2
#HS,1,4,80,25,11,1
#C1,R3
~Y~I
~W~IFigure 3.1~Y~I
The RGB Color Model
~G~IG~Y~I
│ Yellow (1,1,0)
~W~I ├──────────────────────────┐
/│~Y~IGreen Only ~W~I /│
/ │ (0,1,0) / │
/ │ / │
/ │ / │
/ │ ~Y~IWhite~W~I / │
~Y~ICyan~W~I / │ ~Y~I(1,1,1)~W~I/ │
~Y~I(0,1,1)~W~I┌───────┼───────────────────┐ │
│ └───────────────────┼──────┴~Y~I─────── ~R~IR~Y~I
│ / ~Y~I(0,0,0)~W~I │ / ~Y~IRed Only~W~I
│ / │ / ~Y~I(1,0,0)~W~I
│ / │ /
│ / │ /
│ / ~Y~IBlue Only~W~I │ /
│ / ~Y~I(0,0,1)~W~I │/
└───────────────────────────┘ ~Y~IMagenta (1,0,1)
/
~C~IB~Y~I
#WN
#BO,4,15,78,20,7,1,0,4,15,2
Each point within the volume of the cube can be defined by the
coordinates (R,G,B), where the values for R, G, and B represent the
amounts of red, green, and blue that are present in the particular
color.
#WP
%
#EF
#T15,1,Chapter 3 Using Color Pg. 3
#HS,1,4,80,25,11,1
#C4,R5
~Y~I
~W~ISubtractive Primary Colors~Y~I - These are the primary colors that, when
subtracted from each other, produce new colors. The subtractive primary
colors are ~M~Imagenta~Y~I, ~C~Icyan~Y~I, and yellow. In this color scheme, cyan minus
yellow gives ~G~Igreen~Y~I. Color liquid crystal displays (LCD) almost always use
the subtractive primary colors.
#WN
~K~W~IHue~Y~I - This is what we normally think of as color. Blue is a hue, as is
yellow.~k
#WN
~W~IChromatic Colors~Y~I - Colors that have hue in them.
#WN
~W~IAchromatic Colors~Y~I - Colors without hue. The achromatic colors are black,
white, and any shade of gray.
#WN
#BO,4,15,78,20,7,1,0,4,15,2
To most people, it sounds odd to say that a hue is what we normally
think of as a color, and then say that the chromatic colors are colors
with hues. That's true. It is odd until you realize that black, white,
and shades of grey are colors with no hue.
#WP
%
#EF
#T15,1,Chapter 3 Using Color Pg. 4
#HS,1,4,80,25,11,1
#C4,R5
~Y~I
~W~IShade~Y~I - A shade is formed by mixing a hue with black.
#WN
~W~ITone~Y~I - A tone of a color is made by mixing that color with gray.
#WN
~W~ITint~Y~I - Tintes are produced by mixing a hue with white.
#WN
Although we won't use these terms too much in this book, understanding them
is important to understanding the literature of computer graphics.
#WP
#X