Update time:2018-09-30 14:02:54 | Clicks:1013

Recently, we get customer inquiry for
measuring CIE-lab and Delta E*00. Today we will introduce the development of color
difference formulaΔE*00, ΔE*94
and ΔE*00.

Firstly, let us introduce some
definition for CIE, ΔE*ab, ΔE*94 and ΔE*00.

**1. What
is CIE-lab and ΔE*ab?**

CIE is the short name of The
International Commission on Illumination. In 1976, it introduced the color
space CIE-lab. The meaning of Lab, please refer to the article “**Do You Know the Meaning of Color Value**”.

Delta-E is a single number representing
the "distance" between two colors. ΔE*ab is also called ΔE*, or,
inaccurately, dE*, dE, or "Delta E".

CIE-Lab and Delta E

**2. What
is ΔE*94?**

In 1994, CIE makes improvement on how to
calculateΔE*ab. The new color different formula is ΔE*94.

**3. Improvement
from ****Δ****E*ab
to ****Δ****E*94.**

The color difference formula of 1976 as
follows

ΔE*ab

There is obviously error, because the
effects of the three channels on the human eye must be different, and the
effects on the human eye under different values of the same channel are not the
same. The figure below shows the chromatic aberration of different regions.

In the above picture, the horizontal
axis is a and the vertical axis is b, so we can see that the larger the
absolute value of a and b, the larger the area of the ellipse, which indicates
the low sensitivity of the human eye to high chroma. Base on the above analysis
, in 1994, CIE improved the color difference formula and new formula is as
follows

ΔE*94

This formula is that when the absolute
values of a and b are large, the sensitivity coefficient is also divided by a
large number. The values of a and b are proportional to their respective
sensitivity coefficients, and the ratios are 0.045 and 0.015, respectively.

**4. Improvement
from ****Δ****E*94
to ****Δ****E*00. **

In fact, this improvement is not enough.
Because it can be seen from the above figure that all the ellipse points to the
coordinate origin except for the blue area in the lower left corner. And for
the blue area, the sensitivity of the human eye is high, that is, the tolerance
for change is low. In fact, the problem of short wavelengths of blue light and
the inability to produce blue light was once a problem in the industry.
Therefore, in 2000, CIE improved the color difference formula again for Blue
light and other issues, and it became the following form:

ΔE*00

This is the color difference formula we still use today. CHNSpec Tech is specialized on manufacturing instruments for color, gloss and haze measurement. New products for transmittance and reflectance measurement benchtop spectrophotometer, new haze meter will come out within this year. Any inquiry, you are welcome to contact us.