Explanation 1: “Light up”

 Generally speaking, the phenomenon of “lighting up” refers to the phenomenon of “homochromatic metamerism”:

Two color samples (one standard and one comparison sample) appear to be of equal color (no color difference or small color difference) under one light source (such as D65), while they exhibit significant color difference under another light source (such as A), which is called the “homochromatic metamerism” phenomenon

For this situation, we can describe it as’ lighting up ‘. That is to say, whether the sample can be matched with the standard sample for color matching depends on selecting a specific light source.

The fundamental reason is that the two samples have different reflections of light (reflection spectrum curves or visible band reflectivity), so it is called “Metamerism”.

The reasons for the “abnormal spectrum” include:

A、The composition of pigments used for staining is different;

B、Different processing methods, etc

Explanation 2: “Jumping lights”

 In fact, when we talk about “Tao light” in daily life, besides the above meaning, there is another layer of meaning:

 It refers to the situation where a single color sample undergoes dramatic color changes under different light sources. At this point, it can be described by “jumping the light”.

So, “jumping the light” can also be said to be a sample.

 For example, the dye engineer at CIBA would say when recommending the dye CIBA DEEP RED: This dye does not jump red under light A.

(The author understands his meaning that although A light source contains a large amount of red and yellow light, the dye CIBA DEEP RED will not feel much redder than under D65 light source.)