Testing perception of colour: What's My JND? 0.0059
Can you beat it? https://www.keithcirkel.co.uk/whats-my-jnd/?r=AkogKP___Bd3
What's My JND?

Find your Just Noticeable Difference in colour perception. How small a colour difference can you actually see?

@nomis Interesting one; 0.0046 - given my eyesight, I wouldn't quite have expected that.