Simone Bianco, Arcangelo Bruna, Filippo Naccari, and Raimondo Schettini, "Color space transformations for digital photography exploiting information about the illuminant estimation process," J. Opt. Soc. Am. A 29, 374-384 (2012)
The color reproduction accuracy is a key factor to the overall
perceived image quality in digital photography. In this framework,
both the illuminant estimation process and the color correction matrix
concur in the formation of the overall perceived image quality. To the
best of our knowledge, the two processes have always been studied
separately, thus ignoring the interactions between them. We
investigate here these interactions, showing how the color correction
transform amplifies the illuminant estimation errors. We demonstrate
that incorporating knowledge about the illuminant estimation behavior
in the optimization of the color correction matrix makes it possible
to alleviate the error amplification. Different strategies to improve
color accuracy under both perfect and imperfect white point
estimations are investigated, and the experimental results obtained
with a digital camera simulator are reported.
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Average Colorimetric Error Obtained
by the Color Correction Matrices Optimized for the Different
Illuminants, Evaluated on the Same Illuminant for Which the
Optimization Is Carried Out
Method
Illuminant
WPPLS
WPPPS
SILL
D48
1.5814
0.8585
0.8213
D55
1.8060
0.7420
0.7175
D65
1.2924
0.7847
0.6454
D75
1.4321
0.7743
0.6333
D100
2.2523
0.7710
0.6871
D200
2.3075
0.9529
0.8745
A
2.9431
1.8278
1.7083
B
2.2336
0.8640
0.8337
C
1.5291
0.6704
0.6289
2000 K
4.7032
3.1238
2.9595
UW
1.3010
1.7990
0.7028
F2
2.2654
1.4226
1.3488
F7
1.4263
3.3418
0.5683
F11
2.6258
1.4277
1.308
Table 2.
Average Colorimetric Error Obtained
by the Color Correction Matrices Optimized Simultaneously for
the Different Illuminants, Evaluated on All the Considered
Illuminants
Illuminant
HILL
HILLA
D48
0.9093
0.9462
0.9325
0.9326
D55
0.7175
0.7574
0.7495
0.7495
D65
0.7952
0.7910
0.7972
0.7971
D75
0.9852
0.9793
0.9886
0.9870
D100
1.4092
1.4049
1.4220
1.4237
D200
2.1496
2.1320
2.1704
2.1699
A
3.1261
3.1356
3.1444
3.1445
B
0.9454
0.9419
0.9507
0.9510
C
0.9482
0.9010
0.9433
0.9442
2000 K
6.1841
6.1806
6.1903
6.1908
UW
0.7674
0.7028
0.7237
0.7239
F2
3.6511
3.6831
3.5429
3.5415
F7
0.9251
0.9644
0.8432
0.8442
F11
3.1802
3.1513
3.0754
3.0770
avg
1.9067
1.9051
1.8910
1.8912
Table 3.
Average Colorimetric Error and
Percentage Colorimetric Accuracy Improvement with Respect to
the Most Performing Strategy, Obtained by All the Proposed
Strategies
Method
Opt. Illuminant
Mean
Improvement
SILL
D48
3.0386
7.31%
SILL
D55
3.1250
4.67%
SILL
D65
3.2782
SILL
D75
3.4274
SILL
D100
3.7436
SILL
D200
4.3225
SILL
A
3.3380
SILL
B
3.0628
6.57%
SILL
C
3.3945
SILL
2000 K
7.9029
SILL
UW
3.1422
4.15%
SILL
F2
3.1371
4.30%
SILL
F7
3.0307
7.55%
SILL
F11
2.9857
8.92%
SILL avg
3.6378
HILL
2.9524
9.94%
HILLA
2.9578
9.77%
MILL
2.2002
32.88%
MILLA
2.7711
15.47%
2.6318
19.72%
Table 4.
Average Colorimetric Error and
Average Slope of the SILL and SILL-WEB Color Correction
Matrices
SILL
SILL-WEB
Opt. Illuminant
Mean
Mean Slope
Mean
Mean Slope
D48
3.5666
1.5056
3.3481
1.3469
D55
3.5170
1.6056
3.3043
1.4844
D65
3.4892
1.7306
3.2642
1.5893
D75
3.4653
1.8283
3.2220
1.7118
D100
3.4615
1.9940
3.2277
1.8201
D200
3.5125
2.2206
3.2706
2.0165
A
4.3060
1.4236
4.0250
1.3379
B
3.6232
1.4563
3.4134
1.2810
C
3.4786
1.7486
3.2524
1.6258
2000 K
5.4033
2.3989
5.2324
2.1032
UW
3.5039
1.5232
3.2892
1.3853
F2
3.8222
1.3453
3.6657
1.2536
F7
3.4308
1.6958
3.2157
1.6033
F11
3.9514
1.1698
3.7766
1.0743
Table 5.
Brief Description of the Color Correction Strategies
Compared
Strategy
Acronym
and Short
Description
Number and Type
of Color
Correction
Matrices
Used
Incorporating
AWB
Knowledge?
Color
Correction
Matrix
Selection/Combining
Scheme
The (optional)
subscript indicates the
optimizing
illuminant
HILL: Hybrid
ILLuminant
One, optimized for all train
illuminants
simoultaneously
No
—
The color correction matrix is
found using
a
uniform a-priori distribution for the
illuminant
probability in Eq. (5)
HILLA:
Hybrid ILLuminant,
Approximated
One, optimized for all
train
illuminants
simoultaneously
No
Linear combination with
uniform weights
of
the SILL color correction matrices
individually
optimized for each train
illuminant
—
MILL: Multiple
ILLuminant
One for each test
illuminant
No
—
Ideal case: used for the
computation of
lower
bound performances for
class
strategies
MILLA: Multiple
ILLuminant,
Approximated
One for each train illuminant
(14)
No
Selection of the color
correction matrix
optimized
for the train illuminant with
the
closest CCT to the one in the scene
—
: Multiple ILLuminant,
Approximated
with 2 nearest
neighbors
One for each train
illuminant (14)
No
Linear combination of
the two color
correction
matrices optimized for the
train
illuminants with the closest CCTs
to
the one in the scene
—
SILL-WEB:
Single ILLuminant with
White-balance
Error Buffer
One, optimized for a
single train
illuminant
Yes
—
The (optional)
subscript indicates the
optimizing
illuminant
MILL-WEB:
Multiple ILLuminant with
White-balance
Error Buffer
One for each test
illuminant
Yes
—
Ideal case: used for the
computation of
lower
bound performances for
class strategies
MILLA-WEB:
Multiple ILLuminant
with
White-balance Error Buffer,
Approximated
One for each train illuminant
(14)
Yes
Selection of the color
correction matrix
optimized
for the train illuminant with
the
closest CCT to the one in the scene
—
: Multiple ILLuminant
with
White-balance Error Buffer,
Approximated
with 2 nearest neighbors
One for each train illuminant
(14)
Yes
Linear combination of the two
color
correction
matricesoptimized for the
train
illuminants with the closest CCTs
to
the one in the scene
—
Table 6.
Average Colorimetric Error and
Percentage Colorimetric Accuracy Improvement with Respect to
the State-of-the-Art Strategy (), Obtained by All the
Proposed Strategies
Illuminant Estimation Algorithm Used
Gray
World (GW)
White Point
(WP)
Gamut Mapping
(GM)
Method
Mean
Improvement
Mean
Improvement
Mean
Improvement
5.2252
4.8796
3.4939
MILL
4.5907
12.14%
3.9803
18.43%
2.9947
16.67%
MILLA
4.9384
5.49%
4.3974
10.97%
3.2210
8.47%
4.7171
9.72%
4.1643
17.18%
3.1119
12.27%
SILL-
4.7260
9.55%
4.4061
10.75%
3.1469
11.03%
MILL-WEB
3.8805
25.73%
3.1978
52.59%
2.5169
38.82%
MILLA-WEB
4.4420
14.99%
4.1272
18.23%
2.9066
20.21%
-WEB
4.2214
19.21%
3.8707
26.07%
2.7857
25.42%
Table 7.
(Color online) Outputs of the Statistical Test for the Color
Correction Strategies Considereda
The sign in the position of the table
means that the strategy is statistically better
than the sampling
(“” sign), statistically
worse (“” sign), or equivalent
(“” sign). The score is the
number of times that a sampling strategy has been
considered statistically better than the others. A
different table is reported for each of the illuminant
estimation algorithms considered: (a) GM, (b) WP, and
(c) GM.
Table 8.
Statistics for the Colorimetric Error Obtained
by the Color Correction Matrices Optimized for the Different
Illuminants, Evaluated on the Same Illuminant for Which the
Optimization Is Carried Out
Illuminant
Method
Min
Mean
Median
Max
Std
D48
WPPLS
0.4179
1.5814
1.3563
3.9946
1.0080
WPPPS
0.0230
0.8585
0.6299
4.3109
0.9612
SILL
0.0114
0.8213
0.5623
4.4062
0.9577
D55
WPPLS
0.4399
1.8060
1.5026
4.9417
1.1727
WPPPS
0.0692
0.7420
0.5533
3.6860
0.8024
SILL
0.0257
0.7175
0.5212
3.6407
0.7831
D65
WPPLS
0.4056
1.2924
0.9478
4.0091
0.9552
WPPPS
0.0171
0.7847
0.6603
3.2856
0.7468
SILL
0.0533
0.6454
0.4674
3.0602
0.6596
D75
WPPLS
0.4080
1.4321
1.2494
3.9956
0.8514
WPPPS
0.0641
0.7743
0.5132
2.8967
0.7017
SILL
0.0760
0.6333
0.4985
2.8013
0.6131
D100
WPPLS
0.7918
2.2523
1.8076
5.1838
1.2901
WPPPS
0.0093
0.7710
0.5056
2.9846
0.7647
SILL
0.0780
0.6871
0.6009
2.8135
0.6404
D200
WPPLS
0.8414
2.3075
2.4154
3.3730
0.6708
WPPPS
0.0217
0.9529
0.6037
3.8108
0.9297
SILL
0.0390
0.8745
0.6948
3.5975
0.8381
A
WPPLS
0.7814
2.9431
1.9984
9.7471
2.1096
WPPPS
0.0129
1.8278
1.1124
9.1925
2.1240
SILL
0.0491
1.7083
0.8344
8.9678
2.1411
B
WPPLS
0.2074
2.2336
1.8791
5.8973
1.7048
WPPPS
0.0317
0.8640
0.6627
4.1517
0.9303
SILL
0.0292
0.8337
0.6168
4.3472
0.9624
C
WPPLS
0.4818
1.5291
1.3728
3.0041
0.6567
WPPPS
0.0396
0.6704
0.4380
3.0910
0.7027
SILL
0.0279
0.6289
0.4475
2.9747
0.6605
2000 K
WPPLS
1.9435
4.7032
4.2830
8.0833
1.8531
WPPPS
0.5961
3.1238
1.6654
14.2835
3.2635
SILL
0.2112
2.9595
1.4862
15.3819
3.6402
UW
WPPLS
0.1984
1.3010
1.2808
2.9917
0.7966
WPPPS
0.1286
1.7990
1.2915
6.1698
1.5562
SILL
0.0915
0.7028
0.5855
3.0210
0.6685
F2
WPPLS
0.5355
2.2654
1.7426
4.9969
1.2462
WPPPS
0.0037
1.4226
0.6329
4.8860
1.4983
SILL
0.0036
1.3488
0.8667
5.5046
1.4042
F7
WPPLS
0.6094
1.4263
1.4061
2.6802
0.5767
WPPPS
0.0970
3.3418
3.1368
10.8883
2.9092
SILL
0.0110
0.5683
0.4116
2.9742
0.6324
F11
WPPLS
0.7488
2.6258
2.3248
8.1779
1.8282
WPPPS
0.0129
1.4277
0.9201
5.2315
1.4583
SILL
0.0054
1.3085
0.8711
6.1566
1.4445
Table 9.
Average Colorimetric Error Obtained
by the Color Correction Matrices Optimized Individually for
the Different Illuminants, Evaluated on All the Illuminants
Considered
Viewing Illuminant
Opt. Illuminant
D48
D55
D65
D75
D100
D200
A
B
C
2000 K
UW
F2
F7
F11
Avg.
D48
0.8213
0.8317
1.0129
1.2220
1.6491
2.3626
2.8787
0.8723
1.1586
6.0337
0.9039
3.5215
1.0178
2.9638
1.9464
D55
0.9093
0.7175
0.7952
0.9852
1.4092
2.1496
3.1261
0.9454
0.9482
6.1841
0.7674
3.6511
0.9251
3.1802
1.9067
D65
1.1327
0.8442
0.6454
0.7357
1.1323
1.8831
3.4034
1.1794
0.7225
6.3473
0.8435
3.9105
1.0456
3.5043
1.9521
D75
1.3468
1.0297
0.7414
0.6333
0.9256
1.6689
3.6139
1.3973
0.6573
6.4685
1.0264
4.1693
1.2333
3.7911
2.0502
D100
1.7653
1.4380
1.0913
0.8645
0.6871
1.2904
3.9945
1.8143
0.9547
6.6999
1.4309
4.7326
1.6906
4.3710
2.3447
D200
2.5161
2.1995
1.8357
1.5540
1.1329
0.8745
4.6530
2.5532
1.6620
7.1161
2.1830
5.6369
2.5495
5.2055
2.9766
A
2.1816
2.4159
2.6934
2.9193
3.3120
3.9167
1.7083
2.1853
2.8036
5.1161
2.4118
3.4623
2.6127
2.7670
2.8933
B
0.8511
0.8259
1.0160
1.2312
1.6613
2.3652
2.9022
0.8337
1.1192
6.0660
0.8528
3.5571
1.0447
2.9772
1.9503
C
1.2740
0.9760
0.7198
0.6609
0.9909
1.7328
3.5564
1.3010
0.6289
6.4578
0.9490
4.1136
1.2004
3.7020
2.0188
2000 K
6.6634
6.8535
7.0755
7.2447
7.5241
7.9369
5.3768
6.6859
7.1736
2.9595
6.9148
7.4405
7.0510
6.8837
6.6989
UW
0.9462
0.7574
0.7910
0.9793
1.4049
2.1320
3.1356
0.9419
0.9010
6.1806
0.7028
3.6831
0.9644
3.1513
1.9051
F2
3.1898
3.2267
3.3946
3.5966
4.0300
4.7823
3.8891
3.2199
3.5582
6.6765
3.2962
1.3488
2.6552
2.1881
3.5037
F7
1.1856
1.0180
1.0394
1.1953
1.6242
2.4070
3.3278
1.2051
1.1908
6.3351
1.0176
3.1048
0.5683
2.9159
2.0096
F11
2.3482
2.4477
2.6733
2.8996
3.3302
4.0055
3.0374
2.3541
2.7909
5.9770
2.4343
2.1346
2.2188
1.3085
2.8543
Tables (9)
Table 1.
Average Colorimetric Error Obtained
by the Color Correction Matrices Optimized for the Different
Illuminants, Evaluated on the Same Illuminant for Which the
Optimization Is Carried Out
Method
Illuminant
WPPLS
WPPPS
SILL
D48
1.5814
0.8585
0.8213
D55
1.8060
0.7420
0.7175
D65
1.2924
0.7847
0.6454
D75
1.4321
0.7743
0.6333
D100
2.2523
0.7710
0.6871
D200
2.3075
0.9529
0.8745
A
2.9431
1.8278
1.7083
B
2.2336
0.8640
0.8337
C
1.5291
0.6704
0.6289
2000 K
4.7032
3.1238
2.9595
UW
1.3010
1.7990
0.7028
F2
2.2654
1.4226
1.3488
F7
1.4263
3.3418
0.5683
F11
2.6258
1.4277
1.308
Table 2.
Average Colorimetric Error Obtained
by the Color Correction Matrices Optimized Simultaneously for
the Different Illuminants, Evaluated on All the Considered
Illuminants
Illuminant
HILL
HILLA
D48
0.9093
0.9462
0.9325
0.9326
D55
0.7175
0.7574
0.7495
0.7495
D65
0.7952
0.7910
0.7972
0.7971
D75
0.9852
0.9793
0.9886
0.9870
D100
1.4092
1.4049
1.4220
1.4237
D200
2.1496
2.1320
2.1704
2.1699
A
3.1261
3.1356
3.1444
3.1445
B
0.9454
0.9419
0.9507
0.9510
C
0.9482
0.9010
0.9433
0.9442
2000 K
6.1841
6.1806
6.1903
6.1908
UW
0.7674
0.7028
0.7237
0.7239
F2
3.6511
3.6831
3.5429
3.5415
F7
0.9251
0.9644
0.8432
0.8442
F11
3.1802
3.1513
3.0754
3.0770
avg
1.9067
1.9051
1.8910
1.8912
Table 3.
Average Colorimetric Error and
Percentage Colorimetric Accuracy Improvement with Respect to
the Most Performing Strategy, Obtained by All the Proposed
Strategies
Method
Opt. Illuminant
Mean
Improvement
SILL
D48
3.0386
7.31%
SILL
D55
3.1250
4.67%
SILL
D65
3.2782
SILL
D75
3.4274
SILL
D100
3.7436
SILL
D200
4.3225
SILL
A
3.3380
SILL
B
3.0628
6.57%
SILL
C
3.3945
SILL
2000 K
7.9029
SILL
UW
3.1422
4.15%
SILL
F2
3.1371
4.30%
SILL
F7
3.0307
7.55%
SILL
F11
2.9857
8.92%
SILL avg
3.6378
HILL
2.9524
9.94%
HILLA
2.9578
9.77%
MILL
2.2002
32.88%
MILLA
2.7711
15.47%
2.6318
19.72%
Table 4.
Average Colorimetric Error and
Average Slope of the SILL and SILL-WEB Color Correction
Matrices
SILL
SILL-WEB
Opt. Illuminant
Mean
Mean Slope
Mean
Mean Slope
D48
3.5666
1.5056
3.3481
1.3469
D55
3.5170
1.6056
3.3043
1.4844
D65
3.4892
1.7306
3.2642
1.5893
D75
3.4653
1.8283
3.2220
1.7118
D100
3.4615
1.9940
3.2277
1.8201
D200
3.5125
2.2206
3.2706
2.0165
A
4.3060
1.4236
4.0250
1.3379
B
3.6232
1.4563
3.4134
1.2810
C
3.4786
1.7486
3.2524
1.6258
2000 K
5.4033
2.3989
5.2324
2.1032
UW
3.5039
1.5232
3.2892
1.3853
F2
3.8222
1.3453
3.6657
1.2536
F7
3.4308
1.6958
3.2157
1.6033
F11
3.9514
1.1698
3.7766
1.0743
Table 5.
Brief Description of the Color Correction Strategies
Compared
Strategy
Acronym
and Short
Description
Number and Type
of Color
Correction
Matrices
Used
Incorporating
AWB
Knowledge?
Color
Correction
Matrix
Selection/Combining
Scheme
The (optional)
subscript indicates the
optimizing
illuminant
HILL: Hybrid
ILLuminant
One, optimized for all train
illuminants
simoultaneously
No
—
The color correction matrix is
found using
a
uniform a-priori distribution for the
illuminant
probability in Eq. (5)
HILLA:
Hybrid ILLuminant,
Approximated
One, optimized for all
train
illuminants
simoultaneously
No
Linear combination with
uniform weights
of
the SILL color correction matrices
individually
optimized for each train
illuminant
—
MILL: Multiple
ILLuminant
One for each test
illuminant
No
—
Ideal case: used for the
computation of
lower
bound performances for
class
strategies
MILLA: Multiple
ILLuminant,
Approximated
One for each train illuminant
(14)
No
Selection of the color
correction matrix
optimized
for the train illuminant with
the
closest CCT to the one in the scene
—
: Multiple ILLuminant,
Approximated
with 2 nearest
neighbors
One for each train
illuminant (14)
No
Linear combination of
the two color
correction
matrices optimized for the
train
illuminants with the closest CCTs
to
the one in the scene
—
SILL-WEB:
Single ILLuminant with
White-balance
Error Buffer
One, optimized for a
single train
illuminant
Yes
—
The (optional)
subscript indicates the
optimizing
illuminant
MILL-WEB:
Multiple ILLuminant with
White-balance
Error Buffer
One for each test
illuminant
Yes
—
Ideal case: used for the
computation of
lower
bound performances for
class strategies
MILLA-WEB:
Multiple ILLuminant
with
White-balance Error Buffer,
Approximated
One for each train illuminant
(14)
Yes
Selection of the color
correction matrix
optimized
for the train illuminant with
the
closest CCT to the one in the scene
—
: Multiple ILLuminant
with
White-balance Error Buffer,
Approximated
with 2 nearest neighbors
One for each train illuminant
(14)
Yes
Linear combination of the two
color
correction
matricesoptimized for the
train
illuminants with the closest CCTs
to
the one in the scene
—
Table 6.
Average Colorimetric Error and
Percentage Colorimetric Accuracy Improvement with Respect to
the State-of-the-Art Strategy (), Obtained by All the
Proposed Strategies
Illuminant Estimation Algorithm Used
Gray
World (GW)
White Point
(WP)
Gamut Mapping
(GM)
Method
Mean
Improvement
Mean
Improvement
Mean
Improvement
5.2252
4.8796
3.4939
MILL
4.5907
12.14%
3.9803
18.43%
2.9947
16.67%
MILLA
4.9384
5.49%
4.3974
10.97%
3.2210
8.47%
4.7171
9.72%
4.1643
17.18%
3.1119
12.27%
SILL-
4.7260
9.55%
4.4061
10.75%
3.1469
11.03%
MILL-WEB
3.8805
25.73%
3.1978
52.59%
2.5169
38.82%
MILLA-WEB
4.4420
14.99%
4.1272
18.23%
2.9066
20.21%
-WEB
4.2214
19.21%
3.8707
26.07%
2.7857
25.42%
Table 7.
(Color online) Outputs of the Statistical Test for the Color
Correction Strategies Considereda
The sign in the position of the table
means that the strategy is statistically better
than the sampling
(“” sign), statistically
worse (“” sign), or equivalent
(“” sign). The score is the
number of times that a sampling strategy has been
considered statistically better than the others. A
different table is reported for each of the illuminant
estimation algorithms considered: (a) GM, (b) WP, and
(c) GM.
Table 8.
Statistics for the Colorimetric Error Obtained
by the Color Correction Matrices Optimized for the Different
Illuminants, Evaluated on the Same Illuminant for Which the
Optimization Is Carried Out
Illuminant
Method
Min
Mean
Median
Max
Std
D48
WPPLS
0.4179
1.5814
1.3563
3.9946
1.0080
WPPPS
0.0230
0.8585
0.6299
4.3109
0.9612
SILL
0.0114
0.8213
0.5623
4.4062
0.9577
D55
WPPLS
0.4399
1.8060
1.5026
4.9417
1.1727
WPPPS
0.0692
0.7420
0.5533
3.6860
0.8024
SILL
0.0257
0.7175
0.5212
3.6407
0.7831
D65
WPPLS
0.4056
1.2924
0.9478
4.0091
0.9552
WPPPS
0.0171
0.7847
0.6603
3.2856
0.7468
SILL
0.0533
0.6454
0.4674
3.0602
0.6596
D75
WPPLS
0.4080
1.4321
1.2494
3.9956
0.8514
WPPPS
0.0641
0.7743
0.5132
2.8967
0.7017
SILL
0.0760
0.6333
0.4985
2.8013
0.6131
D100
WPPLS
0.7918
2.2523
1.8076
5.1838
1.2901
WPPPS
0.0093
0.7710
0.5056
2.9846
0.7647
SILL
0.0780
0.6871
0.6009
2.8135
0.6404
D200
WPPLS
0.8414
2.3075
2.4154
3.3730
0.6708
WPPPS
0.0217
0.9529
0.6037
3.8108
0.9297
SILL
0.0390
0.8745
0.6948
3.5975
0.8381
A
WPPLS
0.7814
2.9431
1.9984
9.7471
2.1096
WPPPS
0.0129
1.8278
1.1124
9.1925
2.1240
SILL
0.0491
1.7083
0.8344
8.9678
2.1411
B
WPPLS
0.2074
2.2336
1.8791
5.8973
1.7048
WPPPS
0.0317
0.8640
0.6627
4.1517
0.9303
SILL
0.0292
0.8337
0.6168
4.3472
0.9624
C
WPPLS
0.4818
1.5291
1.3728
3.0041
0.6567
WPPPS
0.0396
0.6704
0.4380
3.0910
0.7027
SILL
0.0279
0.6289
0.4475
2.9747
0.6605
2000 K
WPPLS
1.9435
4.7032
4.2830
8.0833
1.8531
WPPPS
0.5961
3.1238
1.6654
14.2835
3.2635
SILL
0.2112
2.9595
1.4862
15.3819
3.6402
UW
WPPLS
0.1984
1.3010
1.2808
2.9917
0.7966
WPPPS
0.1286
1.7990
1.2915
6.1698
1.5562
SILL
0.0915
0.7028
0.5855
3.0210
0.6685
F2
WPPLS
0.5355
2.2654
1.7426
4.9969
1.2462
WPPPS
0.0037
1.4226
0.6329
4.8860
1.4983
SILL
0.0036
1.3488
0.8667
5.5046
1.4042
F7
WPPLS
0.6094
1.4263
1.4061
2.6802
0.5767
WPPPS
0.0970
3.3418
3.1368
10.8883
2.9092
SILL
0.0110
0.5683
0.4116
2.9742
0.6324
F11
WPPLS
0.7488
2.6258
2.3248
8.1779
1.8282
WPPPS
0.0129
1.4277
0.9201
5.2315
1.4583
SILL
0.0054
1.3085
0.8711
6.1566
1.4445
Table 9.
Average Colorimetric Error Obtained
by the Color Correction Matrices Optimized Individually for
the Different Illuminants, Evaluated on All the Illuminants
Considered