Computes the CIEDE2000 DeltaE value representing the difference between the two colors.
- <= 1.0: difference is not perceptible by the human eye
- 1-2: difference is perceptible through close observation
- 2-10: difference is perceptible at a glance
- 11-49: Colors are more similar than the opposite
- 50-99: Colors are more opposite than similar
- 100: Colors are exactly the opposite