colorscielab

Why is Delta CMC algorithm (for calculating color difference), not symmetric?

I'm implementing the Delta CMC algorithm (color difference in CIELAB space) as described here and here.

I was surprised to see a calculation for the Hue of the first color but not the second color. This would most likely make the algorithm asymmetric. Is this right?

Would it be better to average the Hue of the two colors and use that instead?

Solution

  • You are right, CMC algorithm is really not symmetric. Quote from here:

    the formula is not symmetric, but depends on a standard and a test colour.
Switching standard and test colors changes the difference.