Comparison of Color Difference Methodes for Multi Angle Application Konrad Lex BYK Gardner

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Comparison of Color Difference Methods 
for multi-angle Application 
Konrad Lex, BYK-Gardner GmbH 
10th BYK-Gardner User Meeting, Innsbruck Austria – April 2013 
Page 2, BYK-Gardner GmbH, Comparison of Color Difference Methods for multi-angle Application 
Effect Coatings 
70% of todays automotive finishes are effect coatings 
• Pearlescent coatings result in a 
more spectacular color effect: 
Color Flop 
• Metallic coatings 
accentuate the curved 
profile: Light – Dark Flop 
• Effect finishes with special glitter effect 
(XirallicsTM) 
Page 3, BYK-Gardner GmbH, Comparison of Color Difference Methods for multi-angle Application 
L* = 100 
+a* 
-a* 
+b* 
-b* Blue 
Red 
Green 
Yellow L* = + 58,12 
a* = + 30,41 
b* = + 36,26 
L* = 0 
CIELab - System: L*a*b*- Coordinates 
Page 4, BYK-Gardner GmbH, Comparison of Color Difference Methods for multi-angle Application 
E* = √ (L*)2 + (a*)2 + (b*)2 
 = Sample - Standard 
- + 
 
- + 
- + 
 L* 
 a* 
 b* 
Sample 
E* L* 
b* 
a* Standard 
CIELab - System: Color Difference L*, a*, b* 
Page 5, BYK-Gardner GmbH, Comparison of Color Difference Methods for multi-angle Application 
L* = 100 
+a* 
-a* 
+b* 
-b* 
270° 
0° 
180° 
90° 
L* = + 58,12 
C* = + 47,32 
h° = 50° 
L* = 0 
h° 
C* 
CIELab - System: L*C*h°- Coordinates 
Page 6, BYK-Gardner GmbH, Comparison of Color Difference Methods for multi-angle Application 
+a* 
Sample 
Standard 
C*ab 
h°ab h°ab 
C*ab 
+H* 
+b* 
CIELab - System: Color Differences C* und H* 
E* = √ (L*)2 + (C*)2 + (H*)2 
-C* 
Page 7, BYK-Gardner GmbH, Comparison of Color Difference Methods for multi-angle Application 
CIELab - System: Chromatic – Non Chromatic 
+ b* 
- b* 
+ a* - a* B 
P 
 C* 
 H* 
Non-chromatic colors: C* < 10 
 
 Use L*a*b* 
Chromatic colors: C* > 10 
 
 Use L*C*h° 
Page 8, BYK-Gardner GmbH, Comparison of Color Difference Methods for multi-angle Application 
CIELab - System: Typical Tolerances 
0.5 0.5 1.0 45° 
b* a* L* 
Metallics 
0.5 0.5 1.0 45° 
Solids 
0.5 0.5 1.0 110° 
0.5 0.5 1.0 75° 
0.7 0.7 1.5 25° 
1.0 1.0 2.0 15° 
-15° 1.0 1.0 2.0 
*Measurement of Metallic & Pearlescent Colors 
Allan Rodrigues, DuPont, 1990 
Achromatic 
Page 9, BYK-Gardner GmbH, Comparison of Color Difference Methods for multi-angle Application 
CIELab - System: Typical Tolerances 
110° 1.0 
1.0 75° 
1.0 2.0 1.5 
 
45° 
25° 
15° 
-15° 
H* C* L* 
1.0 2.0 
1.0 2.0 
1.2 2.2 
1.5 2.5 
1.5 2.5 
2.0 
3.0 
3.0 
Chromatic 
Metallics 
1.0 2.0 1.5 45° 
Solids 
Page 10, BYK-Gardner GmbH, Comparison of Color Difference Methods for multi-angle Application 
Color Difference 
Delta CIE Lab: 
What causes the problem? 
Compare to tolerances: 
 dH* is too large! 
Page 11, BYK-Gardner GmbH, Comparison of Color Difference Methods for multi-angle Application 
Weighted Color Difference 
 
CMC – Color Difference Formula 
Delta E cmc: 
Page 12, BYK-Gardner GmbH, Comparison of Color Difference Methods for multi-angle Application 
Weighted Color Difference 
 
CMC – Color Difference Formula 
H S 
c cS 
lS L 
• 3-dimensional ellipsoid with axes corresponding to 
 hue, chroma and lightness 
 
• Weighting functions (= semi-axis) SL, SC and SH 
 are dependent on color of standard 
 
• Factors l and c modify the lengths of relevant 
 semi-axes 
( ) 
2 1 
2 
ab 
2 
ab 
2 
: CMC 
* H * C * L 
E 
 
 
 
 
 
 
 
 
 
 
  
 
  
+ 
 
 
  
 
  
+ 
 
 
  
 
  
=  
H C L 
c l 
S cS lS 
   
Page 13, BYK-Gardner GmbH, Comparison of Color Difference Methods for multi-angle Application 
Weighted Color Difference 
 
General Color Difference Formula 
 measurement geometry 
 application parameter e.g. batch or production 
 weighting factor 
 tolerance 
222
)(
)(*
)(
)(*
)(
)(*
)( 







+







+







= 





bbaaLL
w
Sg
b
Sg
a
Sg
L
E
Achromatic: 
Chromatic: 
222
)(
)(*
)(
)(*
)(
)(*
)( 







+







+







= 





HHCCLL
w
Sg
H
Sg
C
Sg
L
E

g
S
Sg 
Page 14, BYK-Gardner GmbH, Comparison of Color Difference Methods for multi-angle Application 
Weighted Color Components 
 
 
Achromatic: 
Chromatic: 
)(
)(*
)(


L
w
Tol
L
L

=
)(
)(*
)(


a
w
Tol
a
a

=
)(
)(*
)(


b
w
Tol
b
b

=
)(
)(*
)(


L
w
Tol
L
L

=
)(
)(*
)(


C
w
Tol
C
C

=
)(
)(*
)(


H
w
Tol
H
H

=
L
w
, a
w, bw, Cw, Hw < 1.00  within Tolerance 
 
L
w
, a
w, bw, Cw, Hw > 1.00  out of Tolerance 
 
 
Page 15, BYK-Gardner GmbH, Comparison of Color Difference Methods for multi-angle Application 
Weighted Color Difference 
 
CMC – Color Difference Formula 
Delta E cmc: 
Weighted by dE cmc Tolerances 
 dH* is 31% too large! 
Page 16, BYK-Gardner GmbH, Comparison of Color Difference Methods for multi-angle Application 
How to get Tolerances? 
 
Weighted Color Difference Methods 
E‘DIN 
E‘BMW 
Calculation of the 
weighting factors are 
measurement 
geometry dependent 
Weighting factors 
independent from 
measurement 
geometry 
ECMC 
E00 
E‘AUDI2000 
 
Weighting factors 
are dependent on 
lightness flop and 
color flop 
E94 
With Lightness 
Correction 
There is only one standard, DIN 6175-Part 2 for gonio appearant colors 
Page 17 BYK-Gardner GmbH, Comparison of Color Difference Methods for multi-angle Application 
Silver Metallic 
 
Achromatic light metallic 
Page 18 BYK-Gardner GmbH, Comparison of Color Difference Methods for multi-angle Application 
Red Metallic 
 
Chromatic medium light metallic 
Page 19, BYK-Gardner GmbH, Comparison of Color Difference Methods for multi-angle Application 
Yellow Metallic 
 
Chromatic light metallic 
Page 20, BYK-Gardner GmbH, Comparison of Color Difference Methods for multi-angle Application 
Solid White 
 
Achromatic light solid 
Page 21, BYK-Gardner GmbH, Comparison of Color Difference Methods for multi-angle Application 
How to get Tolerances? 
 
Weighted Color Difference Methods 
E‘DIN 
E‘BMW 
Optimized for light 
metallic finishes 
Discontinuity 
between solid and 
gonioapparent colors 
Optimized for solid, 
high chromatic colors 
ECMC 
E00 
E‘AUDI2000 
 
Applicable for 
metallic and solid 
E94 
With Lightness 
Correction 
Page 22, BYK-Gardner GmbH, Comparison of Color Difference Methods for multi-angle Application 
Weighted Deltas 
Unweighted Deltas 
Weighted Deltas 
Unweighted Deltas 
Weighted Deltas 
Page 23, BYK-Gardner GmbH, Comparison of Color Difference Methods for multi-angle Application 
Conclusion 
• All color difference methods with weighting factors 
are closer to the visual than dE* method because 
L, a, b, C and H have different visual 
sensitivities depending on color. 
 
• Gonioappearant colors may end up with 5 to 25 
different tolerances  weighted color componentsmake the life much easier because the tolerances of 
weighted color components are always 1.00 
 
Thank you for your Attention!