Table 1.
Color change classification

Class	Color difference	Color change effect
1	ΔE < 0.2	Invisible changes
2	0.2 < ΔE < 2.0	Very small changes
3	2.0 < ΔE < 3.0	Small changes (color changes visible by high-quality filter)
4	3.0 < ΔE < 6.0	Medium (color changes visible by edium-quality filter)
5	6.0 < ΔE < 12	Big (distinct color changes)
6	ΔE > 12	Different color