Adobe PHOTOSHOP 6.0 Manual page 120

CHAPTER 3
110
Working with Color
• Saturation, sometimes called chroma, is the
strength or purity of the color. Saturation repre-
sents the amount of gray in proportion to the hue,
measured as a percentage from 0% (gray) to 100%
(fully saturated). On the standard color wheel,
saturation increases from the center to the edge.
Brightness is the relative lightness or darkness of
•
the color, usually measured as a percentage from
0% (black) to 100% (white).
Although you can use the HSB model in
Photoshop to define a color in the Color palette or
Color Picker dialog box, there is no HSB mode
available for creating and editing images.
A. Saturation B. Hue C. Brightness D. All hues
RGB model
A large percentage of the visible spectrum can be
represented by mixing red, green, and blue (RGB)
colored light in various proportions and inten-
sities. Where the colors overlap, they create cyan,
magenta, yellow, and white.
A
B
C
D
Because the RGB colors combine to create white,
they are also called additive colors. Adding all
colors together creates white—that is, all light is
transmitted back to the eye. Additive colors are
used for lighting, video, and monitors. Your
monitor, for example, creates color by emitting
light through red, green, and blue phosphors.
Additive colors (RGB)
RGB mode
Photoshop's RGB mode uses the RGB model,
assigning an intensity value to each pixel ranging
from 0 (black) to 255 (white) for each of the
RGB components in a color image. For example,
a bright red color might have an R value of 246,
a G value of 20, and a B value of 50. When the
values of all three components are equal, the result
is a shade of neutral gray. When the value of all
components is 255, the result is pure white;
when the value is 0, pure black.