Huefork
Spot the odd shade, then judge how much darker or lighter it is. 5 rounds, getting subtler.
About Huefork — how small a difference can you see?
Huefork does two jobs at once: it finds the smallest shade difference your eye can detect, then tests whether you can judge how large that difference is and in which direction. This blend of detection and magnitude estimation mirrors real color work, where it is not enough to notice two swatches differ — you have to say by how much, and whether to nudge lighter or darker to close the gap.
Each round you first tap the odd shade among three, then rate how much darker or lighter it looked on a five-point scale. Over five rounds the differences shrink toward your personal threshold.
Your result is a just-noticeable difference, reported as a Delta-E number. Learn about color difference and Delta-E, or browse all our Learn about color guides.