UNDERSTANDING LAB COLOUR VALUES & DE
CIE LAB Color Scale, L*A*B* Color Values & Delta E Color Difference
What Is CIE LAB?
In color measurement, CIE LAB is one of the most used scales. It is applied in a wide variety of industries including paints, plastics, automotive, textiles, packaging, food, and cosmetics. The CIE LAB color scale came about because of the need for a common color language that was close to human perception. The CIE LAB satisfied these requirements and hence the International Commission on Illumination (CIE) replaced the CIE XYZ color scale with it.
What Does L*A*B* Color Value Mean?
Color measured in the CIE LAB color scale is expressed in terms of three coordinates—L*, a*, and b*—in which each one represents the following:
L* – Lightness
a* – Level of redness or greenness
b* – Level of yellowness or blueness
The below table has the interpretation, range, and explanation of each coordinate in the LAB color scale.
Black to White
0 to 100
0 corresponds to Black
100 corresponds to Diffuse White
Green to Red
-128 to 127
-128 corresponds to Green
127 corresponds to Red
Blue to Yellow
-128 to 127
-128 corresponds to Blue
127 corresponds to Yellow
L*A*B* Color Measurement
Colorimeters and color spectrophotometers are instruments that can evaluate the color of a product in objective terms. Almost all colorimeters and color spectrophotometers are designed to produce L*, a*, b* color values. Additionally, they have the ability to compare the colors of two products and compute the difference in each coordinate i.e. ΔL, Δa, and Δb. They provide ΔE, which is the overall color difference calculated by considering the color difference in each coordinate.
How To Perform A Color Test?
Using a colorimeter or color spectrophotometer, it is a simple and straightforward process to perform a color test that involves comparing two products and computing their color difference.
For this, you need the desired color which will be referred to as the ‘Standard’. The product that you want to match against the Standard is referred to as the ‘Sample’.
Color Difference ΔE
The easiest way to interpret a color test is to observe the delta E value and check if it is within tolerance limits. If the color of the sample is found to be within limits, the sample passes, otherwise it fails.
Most colorimeters/color spectrophotometers offer the functionality to set tolerance limits. Once this is done and a sample is tested, the instrument will automatically display if the measured sample is within the set limits.
Before proceeding with the color test, you would first have to determine your tolerance level for ΔE value. You can fix this based on the explanation provided below.
0 – 0.5
Very low difference that is not noticeable to the human naked eye
Acceptable in all industries
0.5 – 1
Minute color differences that can be noticed by trained professionals
Acceptable in most industries except high quality control requirements
1 – 2
Visible color difference, but not obvious
Acceptable in few industries, but rejected in most industries
Obvious color difference
Rejected in almost all industries
Color Spectrophotometers In India
Are you looking for a colorimeter or color spectrophotometer to measure color in the CIE LAB color scale and evaluate delta E color difference?
Agaram Industries is the Indian distributor of color measuring devices from 3nh Technology. To get a quotation with the color measurement device price, you can fill up this form or send an email to firstname.lastname@example.org.
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