The relationship between color measurement density method and CIE L*a*b*

2. Relationship between measurement results and visual judgment

The biggest difference between the density measurement and CIE L*a*b* is that CIE L*a*b* is very close to the color observed by the human eye and therefore works better when used to measure the color of prints, and the density measurement method Differences in dealing with different colors sometimes cause deviations.

For example, we use an X-Rite 530 spectrophotometer to measure two sets of offset printing samples (Figure 1), measure their densities and CIE L*a*b*, and calculate the density difference and color difference ΔE from these data. As shown in Table 1.

From Table 1, we can see that the difference between the density of the first two dark samples is 0.1 and that the naked eye does not look different; the difference between the density of the second two bright samples is 0.12, which is very close to the first group, but at this time the vision The difference is very obvious. Therefore, if the difference in density occurs in the dark area, the customer may not be aware of it. If it occurs in the neutral and midtone color areas, the color difference is very obvious.

Comparing the color difference AE between the two groups of samples, the result is that the ΔE of the two dark samples is equal to 2.3, and the ΔE of the two bright samples is equal to 9.4. They correspond to smaller visual differences and obvious visual differences, respectively, close to the human eye. Observations. Therefore, the CIE L*a*b* density method is more reliable and true when measuring color.
(to be continued)