SECTION 3.9
173
Functions
The
Size
value for an input dimension can be 1, in which case all input values in
that dimension will be mapped to the single allowed value. If
Size
is less than 4,
cubic spline interpolation is not possible and
Order
3 will be ignored if specified.
+1
+1
Range
0
1
-1
2
3
4
5
7 8
9 10 11 12 13 14
15
Samples
Range
0
1
-1
2
3
4
6
7 8
9 10 11 12 13
14
15
Samples
/Decode [-1 1]
/Decode [-1 1.1429]
FIGURE 3.8
Mapping with the
Decode
array
3.9.2 Type 2 (Exponential Interpolation) Functions
Type 2 functions
(PDF 1.3)
include a set of parameters that define an
exponential
interpolation
of one input value and
n
output values:
f
(
x
)
=
y
0
, … ,
y
n
–
1
In addition to the entries in Table 3.35 on page 168, a type 2 function dictionary
includes those listed in Table 3.37. (See implementation note 41 in Appendix H.)
TABLE 3.37 Additional entries specific to a type 2 function dictionary
KEY
TYPE
VALUE
C0
array
array
number
(Optional)
An array of
n
numbers defining the function result when
x
=
0.0. Default value:
[ 0.0 ]
.
(Optional)
An array of
n
numbers defining the function result when
x
=
1.0. Default value:
[ 1.0 ]
.
(Required)
The interpolation exponent. Each input value
x
will return
n
values, given by
y
j
=
C0
j
+
x
N
×
(
C1
j
−
C0
j
), for 0
≤
j
<
n.
C1
N
Values of
Domain
must constrain
x
in such a way that if
N
is not an integer, all
values of
x
must be non-negative, and if
N
is negative, no value of
x
may be zero.
Typically,
Domain
is declared as
[ 0.0 1.0 ]
, and
N
is a positive number. The
Range