Colorimeter measurement principle

The color difference meter is a more accurate color measuring instrument than the human eye. It can simulate the optical measuring instrument that the human eye responds to red, green, and blue light. ° Angle analysis All colors can be perceived and measured by any Lab color scale,

The L axis is the brightness axis, 0 is black, 100 is white;

The a axis is the red and green axis, the positive value is red, the negative value is green, and 0 is a neutral color;

The b axis is the yellow-blue axis, the positive value is yellow, the negative value is blue, and 0 is a neutral color.

These scales can be used to indicate the color difference between the sample and the standard sample, usually with Δa, Δb, ΔL as identifiers, ΔE is defined as the total color difference of the sample, but it cannot indicate the shift direction of the color difference of the sample, ΔE value The larger the value, the greater the color difference.

The color difference meter can measure and display the color difference ΔE and Δa, Δb, ΔL values of the sample and the standard sample according to the Lab and Lch principles of the CIE chromaticity space

ΔE is usually calculated according to the following formula: 

ΔE*=[(ΔL*)+(Δa*)+(Δb*)]1/2

Sometimes some companies require the total color difference to be less than 2, and some also require the Lab value to be reached. If ΔE ≤ 2.0, it is recommended that Δa, Δb, and ΔL be ≤ 1.5. Generally, when ΔE is 1.5, it can be distinguished visually. Since Δa, Δb, and ΔL generally have no fixed values, when the requirements are too strict, there are often requirements for the total color difference ΔE and color difference Δc (regardless of the influence of brightness).