SECTION 4.5
237
Color Spaces
4.5.2 Color Space Families
Color spaces can be classified into
color space families.
Spaces within a family
share the same general characteristics; they are distinguished by parameter values
supplied at the time the space is specified. The families fall into three broad cate-
gories:
•
Device color spaces
directly specify colors or shades of gray that the output
device is to produce. They provide a variety of color specification methods,
including grayscale,
RGB
(red-green-blue), and
CMYK
(cyan-magenta-yellow-
black), corresponding to the color space families
DeviceGray
,
DeviceRGB
, and
DeviceCMYK
. Since each of these families consists of just a single color space
with no parameters, they are often loosely referred to as the
DeviceGray
,
DeviceRGB
, and
DeviceCMYK
color spaces.
•
CIE-based color spaces
are based on an international standard for color specifi-
cation created by the Commission Internationale de l’Éclairage (International
Commission on Illumination). These spaces specify colors in a way that is in-
dependent of the characteristics of any particular output device. Color space
families in this category include
CalGray
,
CalRGB
,
Lab
, and
ICCBased
. Individu-
al color spaces within these families are specified by means of dictionaries con-
taining the parameter values needed to define the space.
•
Special color spaces
add features or properties to an underlying color space.
They include facilities for patterns, color mapping, separations, and high-
fidelity and multitone color. The corresponding color space families are
Pattern
,
Indexed
,
Separation
, and
DeviceN
. Individual color spaces within
these families are specified by means of additional parameters.
TABLE 4.12 Color space families
DEVICE
CIE-BASED
SPECIAL
DeviceGray
(PDF 1.1)
DeviceRGB
(PDF 1.1)
DeviceCMYK
(PDF 1.1)
CalGray
(PDF 1.1)
CalRGB
(PDF 1.1)
Lab
(PDF 1.1)
ICCBased
(PDF 1.3)
Indexed
(PDF 1.1)
Pattern
(PDF 1.2)
Separation
(PDF 1.2)
DeviceN
(PDF 1.3)