CIELAB Color Difference

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