CHAPTER 4
270
Graphics
A
DeviceN
color space is specified as follows:
[ /DeviceN
names alternateSpace tintTransform
]
or
[ /DeviceN
names alternateSpace tintTransform attributes
]
It is a four- or five-element array whose first element is the color space family
name
DeviceN
. The remaining elements are parameters that a
DeviceN
color
space requires.
The
names
parameter is an array of name objects specifying the individual color
components. The length of the array determines the number of components in
the
DeviceN
color space, which is subject to an implementation limit; see Appen-
the name
None
, which can be repeated as described later in this section. (The
special name
All
, used by
Separation
color spaces, is not allowed.)
Color values are tint components in the range 0.0 to 1.0:
•
For
DeviceN
color spaces that do not have a subtype of
NChannel
, 0.0 always
represents the minimum amount of colorant; 1.0 represents the maximum.
Tints are always treated as subtractive colors, even if the device produces out-
put for the designated component by an additive method. Thus, a tint value of
0.0 denotes the lightest color that can be achieved with the given colorant, and
1.0 the darkest. (This convention is the same one as for
DeviceCMYK
color
components but opposite to the one for
DeviceGray
and
DeviceRGB
.)
•
For
NChannel
color spaces, values for additive process colors (such as
RGB)
are
specified in their natural form, where 1.0 represents maximum intensity of col-
or.
When this space is set to the current color space (using the
CS
or
cs
operators),
each component is given an initial value of 1.0. The
SCN
and
scn
operators re-
spectively set the current stroking and nonstroking color. Operand values sup-
plied to
SCN
or
scn
are interpreted as color component values in the order in
which the colors are given in the
names
array, as are the values in a sampled im-
age that uses a
DeviceN
color space.
The
alternateSpace
parameter is an array or name object that can be any device or
CIE-based color space but not another special color space (
Pattern
,
Indexed
,
Separation
, or
DeviceN
). When the color space is set to a
DeviceN
space, if any of