Resolution allows you to pick up different image features, it's not infinite. A zebra pattern will eventually merge into a solid gray color upon shrinking, that

Resolution allows you to pick up different image features, it's not infinite. A zebra pattern will eventually merge into a solid gray color upon shrinking, that's your actual resolution limit. But a single dot or a line surrounded by enough background will still be visible way below this limit because it has enough energy difference to activate a photoreceptor, even though you won't be able to tell its true size or thickness.