Function deltaE2000

Calculates the CIEDE2000 color difference (Delta E) between two colors.

This function implements the CIEDE2000 color difference formula, which is the most advanced and perceptually accurate Delta E calculation method standardized by the CIE. It provides significant improvements over earlier formulas, especially for blue colors and neutral colors.

The calculation involves multiple steps:

1. Calculate chroma values and apply corrections
2. Calculate hue angles with appropriate handling of edge cases
3. Calculate lightness, chroma, and hue differences
4. Calculate weighting functions for each component
5. Apply the final formula with rotation term for improved accuracy in blue regions