Without the black stripes, the gray bars of A and B are plainly the same gray.
Lighter or darker?
White’s illusion
Which gray bars are darker, A or B?
Neither: they are the same gray, though A looks darker.
Why? Surprisingly, it’s the stripe a bar seems to belong to, not its biggest neighbor, that sets how light it looks. A’s bars sit on white stripes, so they look darker.
Picture: Lloyd TheCheeseKing, CC0 · Wikipedia(opens in a new tab)