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Table 2 Five best predictive performance results of each colorimetric sensor

From: Investigation into the predictive performance of colorimetric sensor strips using RGB, CMYK, HSV, and CIELAB coupled with various data preprocessing methods: a case study on an analysis of water quality parameters

Analyte

No.

Chemometric method

Color model

Data preprocessing

R2

Q2

RMSEC

RMSEP

Rx

RMSEPeyes

Mn2+

1

PLS

RGB

S

0.9981

0.9872

1.50

3.42

2.28

5.35

2

MLR, PLS

RGB

F

0.9879

0.9870

3.74

3.45

0.92

3

PLS

RGB

SD

0.9993

0.9845

0.92

3.76

4.08

4

MLR

CMYK

None

0.9893

0.9829

3.53

3.95

1.12

5

PLS

CMYK

F

0.9935

0.9796

2.75

4.31

1.57

Fe2+/Fe3+

1

ULR

CMYK

K

0.8729

0.9632

12.16

5.80

0.48

8.62

2

ULR

CMYK

AK

0.8765

0.9571

11.98

6.26

0.52

3

ULR

RGB

B

0.8794

0.9555

11.84

6.37

0.54

4

ULR

CIELAB

A

0.8857

0.9450

11.53

7.09

0.62

5

ULR

RGB

R

0.8794

0.9555

11.84

6.37

0.54

Cu2+

1

ULR

RGB

B

0.9359

0.8208

24.87

35.83

1.44

48.18

2

ULR

RGB

AR

0.9638

0.8200

18.70

35.90

1.92

3

ULR

RGB

AB

0.9317

0.8196

25.67

35.95

1.40

4

ULR

RGB

R

0.9555

0.8176

20.71

36.15

1.75

5

ULR

CMYK

K

0.9499

0.8132

21.98

36.58

1.66

NO3-

1

MLR

CMYK

F

0.9688

0.9736

29.44

23.55

0.80

33.03

2

PLS

CMYK

D

0.9596

0.9628

33.50

27.96

0.83

3

MLR

CMYK

D

0.9696

0.9624

29.04

28.12

0.97

4

PLS

RGB

I

0.9774

0.9619

25.06

28.28

1.13

5

PLS

CMYK

A

0.9652

0.9614

31.09

28.46

0.92

PO43-

1

ULR

RGB

G value

0.8864

0.9442

12.02

6.38

0.53

9.74

2

PLS

HSV

S

0.8790

0.9439

12.41

6.40

0.52

3

ULR

CMYK

AK

0.8870

0.9397

11.99

6.64

0.55

4

ULR

CMYK

K

0.8813

0.9381

12.29

6.72

0.55

5

ULR

RGB

B

0.8777

0.9380

12.47

6.73

0.54

SO42-

1

PLS

RGB

I

0.9696

0.9705

90.10

78.75

0.87

198.89

2

PLS

CIELAB

None

0.9705

0.9667

88.74

83.64

0.94

3

PLS

CIELAB

SO

0.9568

0.9598

107.35

91.86

0.86

4

PLS

RGB

N

0.9408

0.9583

125.66

93.55

0.74

5

PLS

RGB

None

0.9439

0.9577

122.33

94.25

0.77

pH

1

PLS

RGB

N

0.9996

0.9955

0.08

0.22

2.91

0.74

2

PLS

RGB

SD

1.0000

0.9946

0.03

0.25

9.47

3

PLS

CMYK

N

1.0000

0.9920

0.02

0.30

14.20

4

PLS

CIELAB

None

0.9984

0.9912

0.16

0.31

1.96

5

PLS

RGB

None

0.9999

0.9916

0.03

0.31

10.79

Total hardness

1

PLS

CMYK

F

1.0000

0.9905

0.18

10.22

57.28

48.74

2

PLS

CMYK

None

0.9998

0.9882

2.21

11.37

5.15

3

PLS

RGB

F

0.9999

0.9880

1.58

11.48

7.25

4

PLS

RGB

A

0.9998

0.9817

2.12

14.15

6.67

5

PLS

CMYK

A

0.9997

0.9803

2.27

14.68

6.47

  1. A = Color change (different intensities before and after the chemical exposure), AR = Change of red parameter, B = Intensity of blue parameter, F = Color intensities were subtracted by background, I = Logarithm, N = Normalization, S = Standardization, SO = Standardization of a* and b* parameters, AB = Change of blue parameter, AK = Change of black parameter, D = Absolute value of color change, G = Intensity of green parameter, K = Intensity of black parameter, R = Intensity of red parameter, SD = Standardizatjon of color change, RMSEPeyes = Predictive errors using naked eye,