From looking at the Hex values green "008000" and forestgreen "228b22" seem to be more different from each other than seagreen "2e8b57" and forestgreen "228b22"
If simply add up the difference by counting every step from 008000 to 008001 and 0f8000 to 108000 as one point between green and forestgreen I get 79. When I count the difference between seagreen and forestgreen I get 65.
If I however subjectively look at the color it seems like seagreen and forestgreen are easier to distinguish from each other than green and forestgreen.
Is there a way to calculate how easy it is for average humans to distinguish two colors given the hex values of both colors?
powderblue and lightsteelblue differ by the same metric by only 36 but look to me even more distinguishable than those shades of green above.