You're absolutely right that RGB differences are not very meaningful to humans. I chose to stick with the easiest approach for educational purposes, but I'd lov

You're absolutely right that RGB differences are not very meaningful to humans. I chose to stick with the easiest approach for educational purposes, but I'd love to hear if anyone tries out a different color difference function. Note that the authors tried other types of energy functions in their original papers, ones that didn't simply use color differences. No one energy function seemed to be perfect across a variety of images.