Image Processing Reference
In-Depth Information
Example 6.4
Consider the transformation from device-dependent CMY to device-independent
L*a*b* given by the LUT shown in Table 6.6.
Using tetrahedral interpolation,
find the L*a*b* values corresponding to the
CMY¼
[67 128 54] color patch.
S
OLUTION
The desired CMY¼
[67 128 54] point is inside the tetrahedral, as shown
in Figure 6.10. The CMY values at the eight vertices of the cube are
[xyz]
¼
2
4
3
5
2
4
3
5
2
4
3
5
2
4
3
5
0
85
0
0
85
85
0
170
0
0
170
85
n
000
¼
, n
001
¼
, n
010
¼
, n
011
¼
,
2
4
3
5
2
4
3
5
2
4
3
5
2
4
3
5
85
85
0
85
85
85
85
170
0
85
170
85
n
100
¼
,
n
101
¼
,
n
110
¼
,
and
n
111
¼
TABLE 6.6
Example of a Printer Forward Map (CMY to L*a*b*)
C
M
Y
L*
a*
b*
0
0
0
100.00
0.04
0.00
0
0
85
97.61
4.88
35.21
0
0
170
96.02
7.53
69.72
0
0
255
94.96
8.59
100.00
0
85
0
82.98
29.86
7.28
0
85
85
81.49
23.82
24.18
0
85
170
80.94
17.72
87.70
0
85
255
80.51
19.95
53.95
0
170
0
69.10
55.79
11.76
0
170
85
68.90
48.72
16.33
0
170
170
68.86
44.21
41.85
0
170
255
68.80
41.16
69.85
0
255
0
53.82
86.18
14.25
0
255
85
54.58
78.25
9.65
0
255
170
55.07
73.16
29.49
0
255
255
55.16
70.02
49.03
85
0
0
83.70
13.64
20.44
85
0
85
81.13
20.69
12.47
85
0
170
79.84
24.61
43.54
85
0
255
78.66
26.07
77.41
85
85
0
68.50
15.59
25.42
(continued)
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