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Lab 5.1 CIELAB Color Difference

 

Purpose: Learn how to calculate CIELAB color difference Using CIE L*a*b*C*H* Coordinates

Procedure:

Defined by the Commission Internationale de l’Eclairage (CIE), the L*a*b* color space was modeled after a color-opponent theory stating that two colors cannot be red and green at the same time or yellow and blue at the same time. As shown below, L* indicates lightness, a* is the red/green coordinate, and b* is the yellow/blue coordinate. Deltas for L* (ΔL*), a* (Δa*) and b* (Δb*) may be positive (+) or negative ( -). The total difference, Delta E (ΔE*), however, is always positive.

ΔL* (L* sample minus L* standard) = difference in lightness and darkness (+ = lighter, – = darker)
Δa* (a* sample minus a* standard) = difference in red and green (+ = redder, – = greener)
Δb* (b* sample minus b* standard) = difference in yellow and blue (+ = yellower, – = bluer)

ΔC* (C* sample minus C* standard) = difference in chroma  (+ = Higher chroma, – = lower chroma)

There are four colors in the table below, one Standard and three batches. 

Colors

L*

a*

b*

Lab Standard

71.2

12.8

32.8

Lab Sample 1

71.1

18.7

31.8

Lab Sample2

72.5

13.8

31.0

Lab Sample 3

68.5

13.3

15.5

Now calculate CIELAB color differences for these colors and include all highlighted lines (steps) if possible:

Lab Sample 1 vs. Standard A

Lab Sample2 vs. Standard A

Lab Sample3 vs. Standard A

 

Which batch has less color difference compare to Standard A?

 Fill in the below table with all data. 

Colors

L*

a*

b*

∆L*

∆a*

∆b*

∆C*

∆H*

∆E*

The description of the difference in L*, a*, and b*

Lab Standard

71.2

12.8

32.8

 

Lab Sample 1

71.1

18.7

31.8

 

 

 

 

 

 

 

Lab Sample 2

72.5

13.8

31

 

 

 

 

 

 

 

Lab Sample 3

68.5

13.3

15.5

 

 

 

 

 

 

 

 Examples of calculation:

 

LAB 5.2: Compare your results of CIELAB and Calculate CMC and CIE2000 DE:

Step 1: visit the website:


http://www.brucelindbloom.com/index.html?Calc.html (Links to an external site.)
  

Step 2: Fill the table in below:

Colors

L*

a*

b*

CIELAB (1976)

DE

CMC (2:1)

DE

CIE2000 (1:1:1)

DE

Lab Reference

71.2

12.8

32.8

 

Lab Sample 1

71.1

18.7

31.8

 

 

 

Lab Sample 2

72.5

13.8

31.0

 

 

 

Lab Sample 3

68.5

13.3

15.5

 

 

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