FreePascal implementation of the CIE Delta E Color-Difference formulas.
- https://en.wikipedia.org/wiki/Color_difference
- The CIEDE2000 Color-Difference Formula: Implementation Notes, Supplementary Test Data, and Mathematical Observations, by Gaurav Sharma, Wencheng Wu, and Edul N. Dalal.
- http://zschuessler.github.io/DeltaE/learn/