Table 2. Color difference categorization

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
4	3.0 < ΔE < 6.0	Medium changes
5	6.0 < ΔE < 12.0	Large changes
6	12.0 < ΔE	Different color