| 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 changes (color changes visible by medium-quality filter) |
| 5 | 6.0 < ΔE < 12 | Large changes (distinct color changes) |
| 6 | ΔE > 12 | Different color |