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[Expertise] ΔE used to judge color differences
25/06/2024
What is ΔE* (Delta E)? It is a numerical value used to judge the difference between colors. We call it the total color difference value.
When the measured value is lower, it means the compared colors are closer and the difference cannot be judged. The higher the value means the difference is greater, and the difference can be distinguished by visual inspection. How is the value of ΔE* calculated? As mentioned before in [Professional] Color Talk, we can get the LAB value after measuring the color. When the reference color and the comparison color are converted, we can get ΔL respectively. *, Δa* and Δb*, their respective meanings are as follows:
ΔL* - the difference in lightness between the base color and the comparison color
Δa* - the red and green difference between the base and comparison colors
Δb* - the red and green difference between the base and comparison colors
The higher the value, the greater the difference in color comparison. How can the ΔE* value be calculated? It is as follows:
Color difference discrimination theory verification
0≤△E≤1 The observer will not notice the color difference.
1<△E≤2 Only experienced observers will notice the difference.
2<△E≤3.5 Even an inexperienced observer will notice the difference.
3.5<△E≤5 Obvious color differences will be noticed.
5<ΔE The observer notices two different colors.
In order to improve accuracy and efficiency when conducting product inspection, companies will purchase colorimeter for inspection. As shown in the instrument on the right:
The principle of measuring light with this equipment is to use a set of XYZ filters to simulate and obtain the optical properties of the sample color. The XYZ value is the basis of color science, also known as the CIE color system. We will explain this part separately.