I was pretty shocked when I found out that NFT pictures aren't even stored in the block chain. NFTs are just records on the block chain with links to images stored on ordinary servers.
This is because you (in theory) need the whole blockchain to validate an NFT, so you want to keep it as small as possible.
But since you store the Cryptographic Hash of the image too, you can validate that the image on the server is actually the same one referenced by the blockchain. You could even move it to another server, but it will break the link obviously