What is the ruling on a non-mahram man looking at a picture of a veiled girl when she was young? And is it permissible for a husband to see pictures of his wife when she was a child before she wore the hijab?

It is permissible for a non-mahram and others to look at pictures of girls if they were taken when they were young and not yet desirable at that time, as there is no harm in looking at a young girl who is not yet suitable for marriage.